## 1. Proximal Theories of Sounds



Proximal theories of sounds construe sounds as located at or beneath
the bodily surface of the hearer. We distinguish two main strands.


### 1.1 Sounds as Sensations



Modern philosophical accounts of sounds informed by psychology of
perception construe sounds as "sensations", or
states/properties of hearers. Consider,



> 
> 
> It seems...reasonable to suggest that the sounds directly
> perceived are sensations of some sort produced in the observer when
> the sound waves strike the ear. (Maclachlan 1989: 26)
> 
> 
> 



The sound-as-sensations theory is justified by some facts about
auditory experience. People report hearing voices and bells even when
no one is speaking and no bell is ringing. Various examples of
subjective sounds are documented under the label of tinnitus. In an
anechoic chamber, most subjects experience subjective buzzing and
whistlings. Some subjects undergo pathologic tinnitus when they hear
sounds that disrupt their normal auditory capabilities. When Russian
composer Shostacovich turned his head on a side, he was subject to a
flow of melodies (Sacks 2008). Tinnitus and other subjective auditory
phenomena have different causes, that can be related to the mechanical
properties of the inner ear or to more central features. The objects
of these experiences are naturally and spontaneously categorized as
sounds. If sounds are simply defined as the objects of audition, then
they are easily identified with the qualitative aspects of auditory
perception. Various strands of indirect realism in perception would
make this view mandatory. According to them, it is by hearing the
immediate, proximal items that we hear some distal events or objects.
In such a case sounds would be defined as the immediate objects of
auditory perception.


### 1.2 Sounds as Proximal Stimuli



A bit more peripheral, albeit still proximal, is a position, defended
by (O'Shaughnessy 2000) claiming that the sound heard is where
the hearer is:



> 
> 
> ...while the sound originates at a distance and we can hear that
> it is coming from a direction and even place, and while there is no
> auditory experience of hearing that the sound is where we are, the
> sound that we hear is nonetheless where we are (2000: 447).
> 
> 
> 



This leaves open the possibility that an unheard sound be located away
from the hearer.



Support for this position comes from the following example. If I hear
the noise of a motorcycle far away, the physical event at my ear is
qualitatively different from the physical event that is produced at
the motorcycle's place. If I was close to the motorcycle, the
physical event at my ear would be completely different from, and would
not correspond to that of a motorcycle driving far away. A party
upstairs does not sound the way it sounds to participants to the
party. However, these arguments can be resisted on two counts. First,
one should distinguish between source and informational channel.
Consider a visual analogue. From the fact that reflected light is the
only light that hits the eye, it does not follow that one does not see
reflecting surfaces or is not aware of incident light. Reflected light
contains information about the reflecting object and the illumination,
which is unpacked by the brain. In the case of sound, distance,
echoes, reverberations, and filtering affect the informational channel
in a way that informs about the position of the source. Second, the
examples used to support the proximal theory are unable to account for
the perceived constancy of auditory features of distant objects. The
motorcycle and the party can be judged to be very noisy, even if the
physical events at the hearer are faint because of the distance from
the respective sources. We do possess a notion of distal volume of a
sound.



The locatedness of the sound at the hearer's position entails
that there are as many sounds as there are actual (or potential)
hearers around. An alternate account would consider that one and the
same sound is present which is, however, multiply located.



These examples, and the related difficulties, thus suggest that a
major shortcoming of proximal theories is that they do not locate
sounds where an untutored description of what is perceived suggests
they are. This means that if sounds were inner sensations, or
mechanical events at the ear, we would be almost always mistaken in
our aural perceptions, at least on important aspects of the sound. In
turn, this amounts to accounting for auditory perception in terms of a
massive error theory. We shall see that proximal theories are not
alone in endorsing it.


## 2. Medial Theories of Sounds



Medial theories construe sounds as features of the medium in which a
sounding object and a hearer are immersed. The identification of
sounds with sound waves is the major example of medial theories.


### 2.1 Sounds as Events or Properties of the Medium



When speaking about voice in his treatise *De Anima* (*On
the Soul*), Aristotle wrote that sound is a "certain
movement of air" (*De Anima* II.8 420b12) but, even
though he claimed that sound and motion are tightly connected, he did
not seem to identify them (Pasnau 2000: 32). The natural scientists
of the seventeenth century refined the intuition that sound is a
movement of air into the wave theory of sounds, which appeared to be
an obvious competitor for the quality or sensation (proximal)
view. Galileo registered that 



> 
> 
> sounds are made and heard by us when...the air...is
> ruffled...and moves certain cartilages of a tympanum in our
> ear....high tones are produced by frequent waves and low tones by
> sparse ones. (1623 [1957: 276]) 
> 
> 
> 



Descartes joined in and in his *Passions of the Soul*
considered that what we actually hear are not the objects themselves,
but some "movements coming from them" (1649: XXIII).
Indeed, around 1636, Mersenne measured the speed of propagation of
sound waves.



Both Galileo and Descartes were aware that the medial account was
revisionary relative to a common sense view of sounds, or at least as
revisionary as is the sensation view. Sounds for the wave view or the
sensation view are not what we unreflectively take them to be on the
basis of the content of auditory perception. (Indeed, Galileo himself
endorsed both a proximal theory--sounds as sensations--and a
medial theory, thereby possibly originating a dualist account.) At the
same time Galileo and Descartes, as well as other modern philosophers,
were not particularly keen in detailing the phenomenological content
of auditory perception.


### 2.2 Sounds as Waves



The wave account is, of course, endorsed by modern acoustics. Sounds
are construed as mechanical vibrations transmitted by an elastic
medium. They are thus described as longitudinal waves, defined by
their frequency and amplitude. A vibrating object (the sound source,
such as a moving vocal chord or a vibrating tuning fork) creates a
disturbance in the surrounding medium (say, air, or water). Each
particle of the medium is set in back-and-forth motion at a given
frequency and with a given amplitude, and the motion propagates to
neighboring particles at the same frequency, undergoing an energy loss
that entails a decrease in amplitude. Seen macroscopically, the
propagation of sound is the propagation of a compression in the medium
followed by a depression, that is, the propagation of a wave. The
behavior of each particle is described by a sinusoid that maps the
cyclical pattern of compressions and depressions against time. A cycle
is the complete path of the sinusoid from crease to crease, at the end
of which the particle is back to its starting position. Amplitude is
the distance between creases and valleys in the sinusoid, period is
the distance between a crease and its successor, and frequency is the
number of cycles per time unit.



Contemporary philosophers of perception of the physicalist strand tend
to align themselves on the wave theory (Nudds 2010b, 2018; Kalderon
2017; Meadows 2018). Perkins thus summarizes the view:
"...the sound we hear is identical with the train of
airwaves that stretches from the distant sounding object to our
ear" (1983: 168). And indeed, the physicalist account of sounds
seems to make a good claim to successful reduction of key auditory
phenomena based on the identification of sounds with sound waves in a
medium in which a sounding object (and possibly a hearer) is
present.


### 2.3 Assessing the Wave Theory


#### 2.3.1 Arguments for the wave theory



Many perceptual properties of sounds are neatly explained by the
presence of strong correlations with properties of waves, in
particular pitch and intensity (i.e., volume).


* The felt quality of high pitch is correlated with high
frequencies; low pitch is correlated with low frequencies;
* High volumes are correlated with high, low volumes with low,
amplitudes.
* The directionality of sounds (the fact that they appear to be
"in a direction") is related to the fact that the hearer
is located on a propagation line from the source.
* Even more accomplished is the explanation of particular auditory
effects, such as the Doppler effect, whereby the speed of a sounding
object in motion contributes to a change in the sound's heard
pitch (so that the whistle of an engine passing by is heard to drop in
pitch as it travels past us).



Interestingly enough, the reduction of sounds to waves in a medium is
arguably more successful than the corresponding attempt to reduce
colors to properties of electromagnetic waves. The latter attempt is
affected by some major problems, such as the existence of non-spectral
colors like purple, or the fact that some spectral monochromatic
colors such as orange are seen as being composed colors.


#### 2.3.2 Arguments against the wave theory



However, for all its merits, the medial identification of sounds with
sound waves raises some objections and leaves some matters
wanting.



For instance, there are metameric sounds (as there are metamers among
colors), that is, sounds that feel identical to the ear although the
corresponding medial properties are different. There is no one-to-one
psychophysical correlation between auditory content and sounds as
waves (Churchland 2007: 222). Moreover, ultrasounds, above 20.000 Hz
and infrasounds, below 20 Hz, have the same physical nature as
sounds--they are mechanical vibrations transmitted by an elastic
medium--but they are not audible (as infrared and ultraviolet are
not visible in the domain of colors): do they count as sounds? It
further appears that the relationship between sound and sounding
object remains underspecified. Do sound waves depend upon sounding
objects in the sense in which we usually think sounds (as auditory
events) do?



Most importantly, as happened with proximal theories, medial theories
do not locate sounds where an untutored conception of auditory
perception suggests they are. If sounds were sound waves, we would be
almost always mistaken in our aural perceptions on important aspects,
which fact, once more, amounts to accounting for auditory perception
in terms of a massive error theory.



What is the nature of sounds under the wave theory? Relevant to our
purposes, there are two main metaphysical conceptions about waves, in
both cases construed as individuals. Either (a)
waves are considered to be of the same nature as processes (temporally
extended entities, with temporal parts), or (b)
they are taken as individuals of a peculiar kind. In case (a), it may
be argued that they do not move, for arguably processes do not move
(Dretske 1967), but rather have phases (temporal parts) located at
different spatial regions. Although we do say that the party moved
from John's room to Mary's room, the party was never fully
in either room. Objects like people (John, Mary, Sue, Lynn), on the
other hand, were completely in John's room first, and completely
in Mary's room later. Objects and people moved, as movement
occurs whenever a whole entity is fully first in a place and then in
another. The party did not move, but part of it was in John's
room and part of it in Mary's at different times.



If waves were processes like parties, one would have to construe sound
waves' "movement" in terms of the presence of
different phases of the wave at different spatial locations. However,
one does not hear a sound wave's phase as being at a particular
location, in particular at any of the locations between the source and
oneself. Sound waves do not appear to be perceptually located where
sounds are. A wave-process has some starting phases in the object, and
some end-phases around the perceiver: but perception locates sounds
wholly where the object is.



In
 case (b),
 (sound) waves are different from processes and are peculiar just
because waves move, as individual substances do. But again, if sound
waves move, the corresponding sounds are not generally heard as
moving. (Contrast this case with seeing a sea wave's phase at a
particular place.) Sound waves propagate in all or most directions
from a sounding object, but the corresponding sounds are not actually
heard as propagating in any direction: the only moving sounds are the
sounds emitted by a moving source. It follows that if sounds were
sound waves in this sense, we would not be hearing them as they
are.



Consider an analogy with light. In the realm of vision, the closest
analogue to sounds are the activities of light sources. We perceive
these activities, and we perceive them as located where their sources
are: the emission of a light bulb out there, the glowing of
candlelight over the table, the irradiation of the sun at the horizon;
each with its own respective color. Do we perceive light itself, as
opposed to the events of light emission at light sources? Clearly,
light travels from the source to our eye--if it didn't, we
would not perceive the source. But what we perceive is the emission
event, and not the light. An irrelevant element of disanalogy is
related to the temporal unfolding of sounds and light events
respectively. Typically in the environment light is emitted
continuously, whereas sounds occur episodically and have short lives.
If most light sources were intermittent as in piezoelectric lighters,
or if most objects were buzzing all the time, this element of
disanalogy would be less salient (Pasnau 2007).



In some conditions it looks as if we perceive light rays, e.g., in a
dusty room. But what is actually perceived is a set of particles of
water or of dust that intercept light. In order for a light ray to be
visible, it would have to send information to our eye without the
mediation of interposed matter. Coming back to sounds, the argument
based on the constraint of fidelity to the content of auditory
perception is thus, in a compact form: in order for sound waves to be
audible, they would have to transmit audible information that reaches
our ears. They don't. So we do not hear them. But we do hear
sounds. Hence sounds are not (medial) sound waves.


#### 2.3.3 Arguments for or against the wave theory reassessed



Some other remarks against the identification of sounds with sound
waves in the medium between the object and the perceiver apply
independently of the metaphysical construal of sound waves as
processes or sui generis individuals.



Consider first the fact that sounds are sometimes loud and sometimes
soft; as we have seen, in the wave theory this feature is correlated
with amplitude of the sound waves. However, the location of the sound
plays a role in establishing the correlation. A loud sound, which is
heard as being far from us, is different from a soft sound, which is
heard as being close to us. The spectra of the two sounds are
different. If you want a vivid example, consider what happens if you
amplify the sound of a person who is speaking low. You do not have the
impression of a person who speaks loud. You have, on the other hand,
the impression of having come very close to a low-speaking giant.



In some conditions, however, it can be difficult for us to tell a loud
sound in the distance from a soft sound nearby, because in the part of
space closer to our ears the sound waves that reach us and correspond
to the two sounds can have the same amplitude. (This only holds for an
ideal case of a long lasting sine wave with no sharp attack. This type
of sound is practically distance-proof because having a single
component, the only possible variation is in amplitude, and no other
spectral differences arise.)



Indeed, the fact that the two sine waves have the same amplitude when
they are close to the ear accounts for the indistinguishability of the
two sounds. Nevertheless, the two sounds, even if indistinguishable,
are distinct, whereas the two sound waves are not. A way to put the
difficulty is as follows: a loud sinusoid heard at a distance is still
a loud sinusoid; but the corresponding sound waves decrease in
amplitude. As we have seen discussing proximal theories, we can make
perfect sense of the notion of distal volume of sounds, even in the
case in which we cannot distinguish a loud distant sound from a soft
sound in the vicinity. Something (decrease in amplitude) happens to
sound waves which does not happen to sounds (the distal volume does
not change). Hence it can be argued that on this account too sounds
are distinct from sound waves.



As a matter of fact, one may want to distinguish two possible lines of
argument here:


1. A phenomenological argument, claiming that sometimes we hear a
constant sound (constant in intensity, for instance), even though the
source is moving away from us. Here different sound waves can
correspond to one and the same sound.
2. A metaphysical argument, holding that sometimes the sound waves
corresponding to two sounds are the same while the sounds are clearly
different: a loud sound in the distance, or a faint sound close to us.
Here the very same sound waves can correspond to distinct sounds. The
latter argument is not lethal, but is a useful reminder that there is
no fully developed theory of sounds as medial sound waves as yet.
Should the sound be identified with the sound waves when they reach
the ears, or with the whole train of sound waves from the source to
our ears, or with the sphere filled with sound waves and centered on
the source?



The thesis that sounds are sound waves is also often motivated by the
argument from vacuums. Surely, it is argued, sounds cannot exist in a
vacuum. As Hylas says in Berkeley's *Three Dialogues Between
Hylas and Philonous*, 



> 
> 
> a bell struck in the exhausted receiver of an air-pump, sends forth no
> sound. The air therefore must be thought the subject of sound. (1713
> [1975: 171-172]) 
> 
> 
> 



But is the claim that there are no sounds in vacuums really obvious?
On pain of question begging, it cannot be made to follow from any
particular metaphysics of sounds. In order to assess it on its own
merits, consider once more the analogy between, on the one hand,
sounds and air, and, on the other hand, emission events at light
sources and light. Air is the medium of auditory perception, and light
is the medium of visual perception. The reasoning now is that just as
things can sensibly be taken to have colors in the dark, they can
sensibly be taken to produce sounds in a vacuum.



In the above arguments an important role is played by the following
requirement: *A theory of sounds should be true to the
phenomenological content of auditory perception.* It seems quite
reasonable to require that as sounds are the objects of hearing,
whatever they are should be somewhat revealed in hearing. In point of
fact, there are two ways in which the fidelity to auditory content
requirement can enter the arguments. In a strong version
(O'Callaghan 2009) it may be held that no theory of sounds
"should make the fact of location perception a wholesale
illusion" (2009: 29); hence, as sounds are represented as
located, it would follow that they are correctly so represented. It
may be argued that this principle is too strong because it is
unjustifiably specific. Why should location, among all possible
features of sounds, be protected against the possibility of systematic
illusion?



In another, weaker version (Casati & Dokic 1994) it is the
representational power of auditory content that is appealed to.
Auditory experience has the power to represent sounds, and it has the
power to represent movement (as when one hears the sound of a moving
train's whistle). It is then natural to assume that auditory
experience would be able to represent sounds as moving, if sounds were
indeed moving entities by their nature. But such is not the case;
hence auditory experience correctly represents them as firmly located.
This construal of the requirement is compatible with the existence of
systematic, though possibly selective, illusion.



The requirement of fidelity to auditory content may be challenged on a
number of grounds. First, it may be challenged by opposing its
rationale. Auditory content may well be massively illusory, and this
could be just the price to pay for any realist account of sounds.



Possibly there is here an analogue to the case of colors, in which
there is room for selective illusion and for the choice between
realism about location, say, and realism about hue. Most arguments for
the subjectivity of colors start from the existence of strong
correlations between phenomenal hue structures (such as the relation
of complementarity between colors, e.g., red and green, which is
manifest in phenomena such as afterimages or color-blindness) and
neural structures (such as bipolar cells). These arguments then stress
the absence of physical correlates for hue structure (nothing in the
wavelengths corresponding to red and green hues can make one predict
the subjective complementarity between red and green). They finally
conclude that colors are mind-dependent. However, the arguments only
establish the mind-dependence of hue structures, not of colors per se.
The location of colors as "outside the brain" can still be
taken for granted. Brought back to sounds, this form of selective
realism would allow for subjective tonal qualities and for an external
(non proximal) location of sounds.



Second, the requirement of fidelity to auditory content may be
challenged by questioning the phenomenological claim that motivates
it. The move would consist in suggesting that sounds do not have the
strong spatial property of locatedness, but the weaker property of
directionality. The distinction between two senses of
"locatedness" in relation to sounds can be traced back to
Malpas (1965), based on ordinary language arguments, and is echoed in
Urmson (1968) and Hacker (1987: 102 ff.); cf. O'Shaughnessy
(1957). Locatedness in the strong sense specifies an address for the
sound, e.g., by specifying both directionality and distance from the
hearer (thus including egocentrical directionality as a component), or
by locating sounds in allocentric space (e.g., a siren from the boat
at Pier 3). According to a weaker sense of "locatedness",
sounds would only be perceived as "coming from" a certain
direction, without any information about the distance they travel. Now
surely this is not the general case. Although in some cases (e.g., the
decrease in amplitude of a sine wave) it may be difficult or
impossible to tell, say, whether what we hear is a soft sound nearby
or a loud sound far away, in most cases the distinction is perfectly
available to the subject, as we noticed earlier when we introduced the
notion of distal volume: someone screaming in a distance is never
confused with someone speaking low near you ear. Indeed the issue of
the locatedness of sounds is the subject matter of specialized
branches of cognitive science (Blauert 1974; Bregman 1990; Schnupp,
Nelken, & King 2011; Grimshaw & Garner 2015).



Incidentally, claiming that sounds are heard in a direction rather
than at a location mixes up two ways of accounting for auditory
experience: phenomenology on the one hand and commonsense reflections
on the directional transmission of auditory information on the other
hand. The commonsense picture may have been made a bit too
sophisticated by exposure to some physical accounts of sounds.



Finally, the requirement of fidelity to auditory content may also be
challenged by proposing a different phenomenology. For example,
Kalderon (2017) argues that sound is an event that is identical to the
propagation in every direction of a pattered disturbance by means of a
medium, such as air or water (2017: 105). He claims, indeed, that
auditory phenomenology is essentially emanative phenomenology.
According to emanative phenomenology, we hear sound as an
ever-expanding sphere which is the medium disturbance propagating in
every direction from its source. Sound is like 



> 
> 
> an expanding ripple caused by a drop in an otherwise calm body of
> water, except that the sound event occurs in three dimensions, not
> two, and so takes the form of a sphere rather than a circle. (2017:.
> 106) 
> 
> 
> 



When facing the challenge of what we hear when we say we hear birds in
the garden outside or people in the corridor outside our
office--which are cases in which it is clear that auditory
phenomenology is distally locating sounds and not making us hearing
sounds as pervading the surrounding medium--Kalderon replies by
saying that what we hear in these cases as distally located are sound
sources, rather than sounds (2017: 115). Nevertheless, this reply
raises the question of how we make the distinction between hearing
sound as located and sound sources as located. Is there a way to
distinguish their different location phenomenologically? Another
question which might challenge the medial view based on emanative
phenomenology is what are exactly the properties of sound sources
which are audible and which provide us with spatial information on
their location.


#### 2.3.4 Defending the wave theory: giving up fidelity to auditory content



Wave theorists typically give up the requirement that an account of
sound be faithful to auditory content (although they would not
typically acknowledge this; as Pasnau 1999 has remarked, the very same
textbook on sounds may simultaneously endorse a medial, a proximal and
a distal theory). However, wave theorists may also try to reconcile
auditory content with the wave conception. Sorensen (2008) proposes
for instance that it is not a purely auditory phenomenon that we do
sometimes identify and localize objects and events at their
*center*, whenever a center is available. For instance
earthquakes are *localized* (in the epistemic sense) at their
hypocenter, although it is admitted that they are not *located*
at their hypocenter. An earthquake is everywhere it can be felt or
measured. Analogously, according to the wave theorist sounds are waves
in a medium, but they are located at their center (at their origin).
The wave conception considers as relatively benign the error of
locating a sound (i.e., a sound wave) at its center/origin.



An important dialectical limitation of Sorensen's suggestion is
that it does not provide us with an independent argument in favor of
the Wave Theory. The identification of sounds with sound waves is of
course compatible with the fact that we locate sounds at a point (the
sounding object's location) which happens to be the center of
expanding sound waves. However, the analogy with the localization of
earthquakes breaks down at a crucial point. Of course, we can usefully
identify a certain region *as* the center of a particular
earthquake. (In general, earthquakes can be localized at their
hypocenter only when we have at least a rough representation of their
full extension in space.) By contrast, as Sorensen admits, the
auditory system does not identify the sounding object's location
*as* the center of expanding sound waves. Indeed, it does not
identify this location as the center of anything. (Compare the way the
visual system identifies the landing area of a stone thrown in water
as the center of a series of concentric, expanding waves. None of the
sort is available to the auditory system.) Now many entities other
than sound waves are at the object's location when we hear a
sound, including events (monadic or relational, as we shall see
below). Thus, facts about the apparent location of sounds do not
justify the Wave Theory better than the Event Theory; quite the
contrary, given our other independent considerations against the
former approach.


#### 2.3.5 Source medium and environment medium



Several among the previous remarks jointly point to the necessity of
better accounting for the distinction between events in the sounding
thing and events in the surrounding medium. As for sounds, this
distinction is consequent upon the distinction between two kinds of
medium: the source medium (that is, the stuff the thing is composed
of) and the medium proper or environment medium, surrounding the
sounding thing, the one in which the hearer could be immersed as well.
Let us take them in turn. First, a thing is a sounding entity only
insofar the stuff or the stuffs the thing is composed of is or are
vibrating. For a simple example, there are no properties of a tuning
fork which account for its sounding, which are not properties of the
stuff(s) the fork consists of (including shape). A more complex
example is the case of the flute, in which the "sounding
object" is air inside the flute. In both cases a portion of
matter--the source medium--is vibrating.



But, second, do we ever happen to hear events in the medium? We
actually do, but in a somewhat indirect way. Consider the visual
realm. In some cases both a thing and (a part of) a medium between us
and the thing are seen. This happens when we look at things through
irregularly warmed air, or through moving water. In these cases, we
see both the thing and the medium, the thing in an unclear way, and
the medium as that which makes the thing appear in an unclear way.



But these cases are not the norm. Perceptual media are in the norm
cognitively transparent: they are imperceptible insofar as they
transmit without significant alteration information about some
relevant properties of the thing perceived through them. Media become
perceivable when this transmitting function is impaired by some event
or disturbance occurring in them. Auditorily, this occurs in the case
of the Doppler effect. The vibration of the air carries information
both about the sounding object and about the effect its speed has on
the medium.



The affectedness of the medium is a feature which is mostly evident,
and almost pervasive in the case of sounds, because of the relatively
similar size of the phenomena involved at the source and in the medium
proper. Vibrations in the sounding objects are macroscopic phenomena,
of a size which is fairly comparable to the size of the sounding
object itself. Therefore the interaction of these vibrations with the
surrounding medium can easily be a source of misperception, for their
impact on the medium brings about processes which are of the same
order of magnitude of the object involved.


## 3. Distal Theories of Sounds



After proximal and medial theories, one should consider another
candidate for the physical identification of sounds, namely distal
properties, processes or events in the medium inside (or at the
surface of) sounding objects, or in the stuff of the sounding object.
Distal views claim their superiority to non-distal competitors in
virtue of their adherence to the spatial structure of auditory
content. As we have seen, we do hear sounds both as externalized
(hence auditory content is at odds with proximal views) and as
distally located (hence auditory content is at odds with medial
views).



There exist at least four varieties of the distal account of sounds:
the Property Theory, the Located Event Theory, the Relational Event
Theory, and the Dispositional Theory. These accounts all subscribe to
the idea that sounds are distally located, but they differ in
ascribing to sounds different ontological status. Let us take them in
turn.


### 3.1 Sounds as Properties



According to the Property View sounds are properties of material
objects just like colors and shapes.



The property view is in part endorsed by the founding fathers of
modern philosophy of perception, Galileo and Locke, who opened a
tradition of lumping various sensory items in the class of secondary
qualities. The typical seventeenth century list of secondary qualities
includes colors, smells and sounds. No significant internal
metaphysical differentiation is made within the class of sensory
qualities, hence the charge of an oversimplification cannot be
directly addressed to historical accounts. Other philosophers may have
added shapes to the list (as Berkeley did), without addressing the
issue of the homogeneity of the class: the issue was only whether
shapes are secondary as sounds are, not whether they are on a par with
sounds as to their structure.



The Property View has contemporary endorsers (Pasnau 1999; although
Pasnau takes sounds to be properties like colors, he comes close to
the event view when he writes that sounds "either are the
vibrations of [objects that have sounds], or supervene on those
vibrations" [1999: 316]; indeed Pasnau 2007 rejoined the Event
Theory). Leddington (2019) also defends a property view of sound
within a distal view positions, since he claims that sound itself is
not an event but it is a property of the event which is producing it
(i.e., a property of the collision).



The property view faces a number of objections. First, we ordinarily
describe objects as "having" colors or shapes, but we do
not ordinarily describe sources as "having sounds".



Rather, we say that they make or produce sounds (conversely, a red
table does not "produce" or "make" red). This
is an ordinary language argument, and as such it might not be very
strong.



The main consideration against the Property View is that it
underestimates the important differences between colors and shapes on
the one hand, and sounds on the other hand. The latter, unlike the
former, are dynamic dependent individuals. And even if colors and
shapes can be theoretically conceived as individuals, they are not
dynamic. Sounds take up time. They start and cease. They are
intrinsically temporal entities. Their temporal profile is essential
to individuating them, in a way which has no analogue in the case of
colors and shapes. However, Roberts (2017) explicitly defends the
Property View by discussing salient disanalogies between sound and
colors. He also suggests a very exhaustive taxonomy of the different
positions available within the property view space. Cohen (2010),
although not directly endorsing the property view, criticizes
arguments that conclude to an asymmetry between sounds and colors, in
particular with regard to temporality.



Di Bona and Santarcangelo (2018: chapter 4) discuss to a certain
length the relationship between sound and time, especially when this
relationship grounds a metaphysical difference between sounds and
colors. They investigate different temporal experiences of sounds and
conclude that temporal experiences of sounds are similar to some
temporal experiences of colors. Sounds and colors differ with regard
to temporality only insofar as one focuses on the role that time plays
when the auditory system has to segregate auditory stimuli into
auditory streams (Bregman 1990). When segregating colors, space is far
more important than time. For a discussion of vision and audition with
regard not only to sounds and colors but also to auditory and visual
objects and always with relation to spatiality and temporality (see
O'Callaghan 2008; Kubovy & Schutz 2010; and Di Bona &
Santarcangelo 2017).


### 3.2 Sounds as Located Events



In this and the following section, we shall present two Event Theories
of sounds, for which we use two distinct labels. An earlier one, The
Located Event Theory, was defended by Casati and Dokic (1994). It has
been rejoined by Pasnau (2009) and extended to the field of sonic art
by Roden (2010). A second, more recent version, the Relational Event
Theory, has received an articulated defense by O'Callaghan
(2007, 2010a). The two accounts agree on categorizing sounds as
events, that is, located temporal particulars, and diverge on some
specifics of the class of particulars that are admitted to be sounds.
The Relational Event Theory makes sounds depend upon the existence of
a medium that carries information about them. In this sense, only a
subclass of situations involving sounds for the Located Event Theory
are situations involving sounds for the Relational Event Theory.


#### 3.2.1 The located event theory



According to the Located Event Theory, sounds are events happening to
material objects. They are located at their source, and are identical
with, or at least supervene on, vibration processes in the source. On
this view (Casati & Dokic 1994), auditory perception of sounds
requires a medium which transmits information from the vibrating
object to the ears; however, the transmitting medium is not essential
to the existence of sounds. One can see at once the fit of this view
with those features of sound which were sources of trouble in the
cases discussed above when criticizing proximal and medial
theories.


1. Vibration processes in the sounding object do not move any more
than sounds appear to.
2. They do not propagate from the object, as much as sounds do not
appear to.
3. Distal volume is constant: Like sounds, and unlike sound waves in
the ambient medium, the intensity of vibration processes can remain
the same through a period of time, even if one distances oneself from
the source and hence hears them as less loud.
4. Finally, and most importantly, tuning-forks and other sounding
objects can be taken as continuing to vibrate irrespective of their
being or not being immersed in a vibrating medium. One does not create
sounds by surrounding vibrating objects with a medium--one simply
reveals them.



A by-product of the Located Event Theory is that it makes plain what
category sounds belong to, as opposed to views that construe sounds
generically as qualities. Sounds are either instantaneous events or
temporally extended processes. They start and cease. They are
intrinsically temporal entities.



Another feature of the Located Event Theory is that it provides us
with a clear example of the compatibility of a theory of non-direct
perception, according to which we hear external events by hearing
their perceptual deputies, with a non-phenomenalistic theory,
according to which perceptual deputies are not mental items. The case
of sound perception shows that there can be indirect perception
without mental deputies. We hear coaches and telephones by hearing
their sounds, i.e., by hearing some (cluster of) vibratory processes
or events occurring in those objects. Sounds are both physical events
and perceptual deputies.


#### 3.2.2 Objections to the located event theory



We shall now briefly discuss some objections to the identification
proposed by the Located Event Theory, as they allow us to highlight
certain metaphysically interesting features of sounds.


##### Imprecise Location and Echoes



The first objection concerns sound location. Even if sounds are heard
as located, it could be held that location is often imprecise or even
erroneous, this in turn depending on--and being explained
by--the nature of sound waves. Here is a relatively common echo
example. Suppose you walk under the rain, your umbrella open. At some
point you enter a building with a glass roof. Rain drops on the roof,
and no longer on your umbrella. The umbrella attenuates the noise from
the roof, which is reflected by the ground. You hear the raindrops as
if they were below you, and not above you. Erroneous location is here
explained by the path of sound waves.



The temptation of identifying sounds with sound waves can arise
because of this fact: that sounds can be mislocated in audition. They
can be heard as located in a region which is larger than, or removed
from, the one occupied by a sounding object, a region which it is
reasonable to take as being occupied by sound waves.



This example poses no particular threat to the distal view. Consider
again a visual analogy. Seeing an object in a mirror is not seeing
another, immaterial object located in an immaterial space beyond the
mirror-plane. There is no such immaterial object; we see one and the
only material object, and we locate it incorrectly as if it was behind
the mirror.



The mirror sophism should be credited to Hobbes'
*Leviathan* (1651: I, I; cf. Casati & Dokic 1994:
49-51), which explicitly linked perception in a mirror and
perception of echoes:



> 
> 
> The cause of sense, is the external body, or object, which presseth
> the organ proper to each sense, either immediately, as in the taste
> and touch; or mediately, as in seeing, hearing, and smelling; which
> pressure, by the mediation of the nerves, and other strings and
> membranes of the body, continued inwards to the brain and hearth,
> causeth there a resistance, or counter-pressure, or endeavour of the
> earth to deliver itself, which endeavour, because outward, seemeth to
> be some matter without. And this seeming, or fancy, is that which men
> call sense; and consisteth, as to the eye, in a light, or colour
> figured; to the ear, in a sound...if those colours and sounds
> were in the bodies, or objects that cause them, they could not severed
> by them, as by glasses, and in echoes by reflection, we see they are;
> where we know the thing we see is in one place, the appearance in
> another.
> 
> 
> 



The deviant paths of sound waves (in echoes) is responsible for the
perceptual difficulty in locating sounds, much as the deviant path of
light rays (in mirrors) is responsible for the analogous difficulty
for visible objects (Casati & Dokic 1994; see also
O'Callaghan 2007 for a lengthy discussion of echoes, and Fowler
2013 for arguments against O'Callaghan's view). But it is
not the case that sound waves are sounds just because of their
responsibility. From the fact that a subject hears something as
imperfectly located, it does not follow that she hears something which
is imperfectly located.


##### Doppler Effect



The second objection concerns typical acoustical effects, like the
Doppler effect, which are perfectly accounted for by appealing to
(medial) sound waves. The Doppler effect is a shift in frequency of
the sound heard by an observer who moves relative to the sound source.
As waves in the direction of movement are compressed, and waves in the
opposite direction are expanded, the frequency drops dramatically when
the hearer and the source go past each other. Such explanations of the
Doppler effect are harmless for a distal account. The Doppler effect
is dependent on something going on in the medium, but this should not
allow one to conclude that what we hear are sound waves in the medium.
The situation can be described as follows in a way that is relatively
uncommitting: When we hear sounds as undergoing the Doppler effect, we
do not hear anything different from a vibration process in a sounding
object, a process which is heard in a sort of perspectival shortening
because the movement of the sounding object causes, among other
things, the Doppler effect.



As a matter of fact, the objection could be turned on its head. On a
train passing by, a trumpet player is delivering a concert. According
to the distal view, the melody does not change, it is just perceived
as changing. If we repeated the experience a number of times, we would
find it suspect that the melody's key drops only when the train
passes by. Surely, we would infer, there is something wrong with the
medium that blocks our perception of the true melody. And surely the
train passengers would disconfirm our impression: they do not hear any
key drop. The medial theory here indeed predicts that there are two
melodies, the one that we hear from the platform, and the one the
passengers hear.


##### Properties of Sounds



A third objection is as follows. 



> 
> 
> Sounds are phenomenologically high or low (they have high or low
> pitch). But processes in objects cannot be high or low. Therefore
> sounds are not processes in objects. 
> 
> 
> 



This can be answered in the following way. Notice first that sound
waves fare no better on this objection--they cannot literally be
said to be high or low. But a more substantial answer is available.
What one needs is a way of systematically correlating predicates like
"...is high", "...is higher
than..." to processes in sounding objects. It is likely
that a high sound corresponds to a quickly vibrating process, and so
forth.


##### The Causal Link



A fourth objection has it that 



> 
> 
> surely there are sound waves in the ambient medium, otherwise no
> causal link could be set between the sounding object and our
> perception of the latter. 
> 
> 
> 



And such sound waves can certainly be measured and physically
described. Now there is no point in denying that there are sound waves
in the ambient medium: of course there are, and they are causally
responsible for our aural perceptions when these are perceptions of
anything at all. A defender of the Located Event Theory ought to just
contend that such sound waves are not what we hear.



Consider an analogy we discussed before. Light is causally responsible
for your perception of an object's surface. But this does not
make you see the light when you see the surface. We can see
luminescent sources, but never light in itself: in order to be seen,
light should have to emit light carrying information about it.


##### Space Filling Sounds?



Finally, another objection concerns the alleged meaningful use of
expressions such "the sound fills the room", "sounds
fill the room". It seems that what makes these sentences true is
best found in the spreading of sound waves, which could actually be
everywhere in the room. But one should not be too much impressed by
idioms. "The sound fills the room" does not describe any
phenomenological fact which is different from the fact that the sound
is audible from any place in the room (in this respect sounds are
unlike fog, which can literally be seen to fill a room).



However, this point deserves closer attention. For sometimes sounds do
seem to fill space. Thunders seem to. This is a case in which the only
vibrating entity is the medium. Nonetheless this case too can be
accommodated by the Located Event Theory: what we hear is sudden
heating of air due to the electric discharge, whose impact is
confusedly propagated by the medium. A portion of air (the portion
that is suddenly heated up) is the vibrating object and another
portion is the transmitting medium.


#### 3.2.3 The relational event theory



According to the Relational Event Theory, sounds are events which
involve both the source and the surrounding medium. They are
relational rather than "monadic" events. (The distinction
between monadic and relational events is not to be taken as cast in
iron, since the latter can be reduced to the former by making the
mereological sum of sources and surrounding medium the subject of
sounds.) O'Callaghan (2002, 2007) has developed such a view at
some length. He notes that the wave conception of sounds is not the
only possible interpretation of Aristotle's remarks about sounds
in *On the Soul*. Aristotle writes that "everything that
makes a sound does so by the impact of something against something
else, across a space filled with air" (*De Anima* II.8
420b15). On O'Callaghan's view, what Aristotle might have
meant is that the sound itself is not a movement of the air, it is
rather the event in which a vibrating object disturbs a surrounding
medium and sets it "moving". Waves in the medium are not
the sounds themselves, but rather the effects of sounds. According to
the Relational Event Theory, sounds are "disturbings" of a
medium, hence depend existentially on a medium that is disturbed and
that will transmit information to a listener. This account differs
from the Located Event Theory insofar as the latter allows for sounds
that exist in a vacuum, and thus distinguishes between a medium that
hosts the vibration and a medium that transmits the vibration.



The Relational Event Theory shares with medial theories an endorsement
of Berkeley's argument that sounds do not exist in a vacuum. It
is, in point of fact, a hybrid theory (O'Callaghan 2007: 55),
sharing with medial theories the tenet of the indispensability of a
medium to the existence of a sound.



An argument against the Relational Event Theory capitalizes upon the
fact that we have the conceptual resources to distinguish between not
hearing a sound because the sounding object is no longer resonating
and not hearing it because we do not have informational access to the
sounding object anymore. The Relational Event theory faces the risk of
collapsing unto a medial position.



To develop this line of thought and make it vivid, imagine a vacuum
jar which has the property of immediately creating a vacuum upon
closing the lid, and of immediately recalling air upon opening the
lid. Take now a sounding object like a tuning fork at 440Hz and have
it vibrate, supposing that the vibration fades and becomes inaudible
after 10 seconds. What you hear is an A that becomes feebler and
feebler until it disappears. Now, place the tuning fork inside the
jar, have it vibrate as before, and repeatedly open-and-close the lid
of the jar, say once in a bit less than a second. What do you hear?
You may have the feeling that a few short sounds, each feebler than
the preceding one, come into existence and pass away. But you may as
well have the impression of a sound that is *revealed* by the
opening and closing of the jar. Indeed, the fading of the sound should
be audible from each "window" to the next, implying that
there is a single sound that fades. If sounds were either sound waves
in the medium surrounding the object, or items dependent on the medium
as per the Relational Event Theory, we would be forced to admit that
the tuning-fork started and ceased to sound; because the relevant
sound waves would not be present in the surrounding medium. Only the
first impression, that of a series of short sounds, would be accounted
for. But the second impression, that of a continuous underlying sound
that is revealed, is supported too. A visual analogue of this would be
the perception of an object in the dark, on which light is shed at
intervals. We would not have the impression that the object gets its
colors and then loses them at intervals.



An advantage of the Relational Event Theory over the Located Event
Theory is that the former provides a criterion for specifying which
among vibratory events at a source are sounds, namely, those that
create medial disturbances that are (or can be) heard. The Located
Event Theorist can, on the one hand, observe that the minimal
requirement of a metaphysics of sounds is to specify which type of
entities are sounds, and not, more specifically, which, among entities
of that type, are sounds. Thus she would claim that sounds are events
at a source, without caring to discuss whether some events at a source
are not sounds. On the other hand, she can observe that too much
fine-grained a classification would create a problem with those events
that share with sounds all interesting metaphysical properties except
for the property of being audible; a problem which, incidentally,
affects a number of physicalist reductions of sounds.


#### 3.2.4 Discussing the located event theory and the relational event theory


##### Relation between sound and sound source



The Relational Event Theory and the Located Event Theory differ
concerning the way in which they account for the audible relationship
between sound and sound source. A manner of characterizing this
relation within the Relational Event Theory is the part-whole
relationship, according to which sounds are heard as the constituent
parts of wholes that are everyday audible events (O'Callaghan
2011a, 2011b). This is a Mereological View, which presupposes a
distinction between sound and the broad event which sound is part of.
The parthood relationship explains a striking and quite ambiguous
aspect of audition, namely, the fact for which we hear the sound and
its source as two different events but, at the same time, we hear them
as not *wholly* distinct.



The advantages of the Mereological View over both the Property
Instantiation view--which claims that sound is heard as a
property of the sounding object--and the Causal View--for
which sound is heard as the effect of its source (O'Callaghan
2011a: 383 and following)--are that:


1. It explains why we often perceive sound as part of a multipartite
occurrence which might also involve inaudible features. For
O'Callaghan, there might be features of the event source that
are not features of sound, and we may hear the sound without
perceiving the features of the event source. For instance, the
happening of "the stomping of the foot" (2011a: 396)
includes non-audible features like a foot stomping or a release of
energy, but also something that we hear, a sound.
2. Mereology explains the intuitive fact that sounds may usually seem
to be heard as *bound* or *unified* with their
sources.
3. Parthood explains the classical Berkeleyan account of auditory
perception for which sound sources are perceived by virtue of the
perception of the sounds they make.



The Located Event Theory proposes a metaphysical Ockhamization of the
Mereological View (Casati, Di Bona, & Dokic 2013), which cleans
the metaphysical landscape up from entities which are not necessary.
As a starting point, it is useful to distinguish between two
components of sound sources: *thing* sources (such as keys or
musical instruments) and *event* sources (such as collisions or
vibratory events at the sounding object) (2013: 462). The Located
Event Theory maintains an Identity View for which sound, instead of
being a proper part of a distinct event that is its source, is
identical with the event source. That is, the collision we hear
*is* the sound we hear. The Identity View appears to simplify
the metaphysical landscape depicted by the Mereological View (2013:
463). The metaphysical claim which grounds the Identity View is
supported by considerations about the phenomenology of audition. These
considerations suggests that we do not commonly hear sounds as part of
larger events--at least when, with "larger events",
we refer to event sources. We hear sounds as a unified entity, and not
as parts of larger events. The biggest price the Identity View has to
pay is for some ordinary language statements to which we have to
renounce, meaning that instead of saying "I heard the bang
(produced by/and) the collision", it would be more appropriate
to say that we heard the collision. This is a disadvantage of the
theory which is acceptable, though, if the advantage is to propose a
plausible theory of sound (2013: 465).



As for the advantages that the Mereological View has over the Property
View and the Causal View, the Identity View can account for them as
well. One of the advantages of the Mereological View is that it
justifies the supposedly different properties that we usually
attribute to sounds and to sound sources. The Identity View responds
to this by arguing that:


1. These differences in the attributable properties are only
apparent. We are tempted to introduce this distinction since it seems
that we ascribe properties to the source and not to sound because of
the non-auditory character of these non-audible properties. But the
Identity View claims that from the fact that some features--such
as the release of energy, vibrations, a painful sensation--are
perceivable through other sense modalities, it does not follow that
such properties are not features of sounds themselves (2013: 464).
Moreover, the extra-properties, if any, can be perfectly ascribed to
the *thing* source.
2. The sense of unification we experience when we hear bangs and
collisions can perfectly be explained in terms of identity.
3. Then Mereological View would explain the Berkeleyan claim for
which we hear the source by virtue of hearing the sound since one
perceives a whole by virtue of perceiving its parts. The Identity View
as well accounts for the Berkeleyan claim since it states that,
because the immediate object of auditory perception is just the event
that is the sound, then, the latter is the thing source we perceive
indirectly by virtue of hearing a sound.



The Identity View and the Mereological View have an equal explanatory
capacity, but the Identity View, in addition to the metaphysical
reduction, seems to untangle the ambiguity of hearing sound and sound
sources as two different events and, at the same time, of hearing them
as not *wholly* distinct. This ambiguity evaporates if we
identify sound with the event source.



Different options concerning the relationship between sound and sound
sources and how we perceive them have been proposed. According to
Matthen (2010) both sounds (and sound composites like melodies,
harmonies or sequences of phonemes) and sound sources can be heard
directly. Leddington supports the Heideggerian view of hearing, for
which we "hear sound sources directly, in hearing the sounds
they make--not, *a la* Berkeley, merely in virtue
of hearing those sounds" (2014: 340). Nudds, instead, suggests
that when listening to sounds we hear them as apparently being
*produced* by the same source (2010a, 2010b). He suggests that
we can also perceive the production of sound bi-modally: by
simultaneously listening to and seeing the cause of sound (2001).



Nevertheless, issues about the relationship between sound and the
thing source (namely, sound and the material object which produces it)
and about how we hear both the objects that produce sounds, and the
relation between objects and sounds still have to be fully worked out
within both views. As a starting point to develop an account on the
perception of sound sources or, at least, of some aspects of the thing
source, Di Bona (2017) proposes an argument for the perception of a
specific characteristic of human voices. She offers an account of how
a certain feature of the sound source when the source is the human
voice is perceivable. Di Bona focuses on gender and engages with the
debate on the admissible content of auditory experience, which has
been mostly developed within the field of visual perception, and
argues for a "rich" view of the auditory experience. This
view is defended by means of the method of contrast applied to a case
of auditory adaptation to human voices. The idea is that we hear not
only the low-level auditory properties of pitch, timbre, and loudness
but also the high-level property of gender, that is, the property
commonly referred to as being a female voice or a male voice. This
high-level property displays adaptational effects and, given that
displaying these effects for a property is a clear mark that this
property is perceivable, then we can conclude we *hear* gender
properties instantiated by human voices. O'Callaghan (2011b)
also engages with the debate on the admissible content of auditory
perception, endorsing a more restricted view on the content of
audition. He focuses on speech perception and argues that we do not
hear the semantic properties of voices (which can also be seen as
properties of sound sources, of voices) since what is auditory
perceivable are, instead, the phonological properties.


##### Some objections to both event theories



Soteriou (2018) claims that both versions of the event theory are too
strict about what they count as sounds: the Located Event Theory
counts as sounds only monadic events happening at material objects;
the Relational Event Theory, instead, admits only relational events
that are bearers of acoustic properties. Soteriou challenges the
assumption that sounds are one kind of thing and suggests that the
sounds we hear are both *pure audibilia* (such as the barking
of a dog), which are events or act-types bearing acoustic properties
that can also be disconnected from their material causes and cannot
exist in a vacuum, and events or act-types that can lack acoustic
properties (footsteps), which are perceivable by means of modalities
that are different from audition, and can exist in a vacuum.
Soteriou's "simple view" or "catholic
view" (2018: 48) moves from the necessity of rejecting the idea
of considering the experiences of echoes and recorded sounds as
illusory experiences or distortion of space and time, which is how he
thinks both event theories regard them in order to be consistent. The
event theories classify the experiences of echoes and recorded sounds
as illusory for the sake of preserving the idea that, usually, sounds
are the bearers of acoustic properties located where we experience
them to be located, namely distally. That is because if sound is
something located at its own source and the echo seems to be a sound
not perceived at its source, then we are hallucinating a sound. When
hearing recorded sound, we experience and illusion since the bearer of
the acoustic properties that we actually hear to be distally located
is distinct from the "original" bearer of acoustic
properties (2018: 44). Soteriou suggests that when hearing echoes or
recorded sounds, even though we do not hear event-like individuals
distally located, we do not have an illusory experience since what we
hear are *pure audibilia*. Soteriou's proposal has the
merit of broadening up the range of the audible, but it might
encounter some worries because of the non-univocal characterization of
what sounds are. For example, a challenge to this view is to explain,
on the one hand, how pure *audibila* are connected to the
physical causes and, on the other hand, how collisions or non-audible
act-types "acquire" acoustic properties that make them
audible.



Nudds (2018) challenges both event theories by virtue of "the
argument from the medium" which is elaborated to show that
environmental events are not the bearers of acoustic features (2018:
54). The main premise of the argument, the existence premise, states
that we can hear a sound without the occurrence of an environmental
event. This premise can be used against both event theories, which
claim that sounds are either identical to environmental events or to
parts of such events (2018: 67). Nudds imagines two situations, S1 and
S2. In S1 there is a disturbance of the medium and an environmental
event, such as a collision; S2 is just like S1 except for the fact
that the disturbance of the medium takes place without that there is
an environmental event. In both situations you hear a sound, but in S2
there is not any environmental event; therefore, it is possible to
have a sound and its acoustic features without the happening of an
environmental event. In order to check whether this conclusion is
true, Nudds elaborates an analogous case within vision and concludes
that while there are two different arguments to show that the premise
is false in vision, none of them apply also to the auditory case. He
asks to imagine to have the situation S3 in which you see a red cube,
and the situation S4 in which we keep the same pattern of light which
determine the appearance of a red cube in S3, except for the fact that
there is no red cube. The arguments to show that the premise is false
in the visual case are as follows.



(1) The premise is false since you cannot see a red cube without that
there is something, a real thing, that is the bearer of the visual
features that usually a red cube has. When it seems to you that you
are seeing a red cube without that there actually is a red cube, it is
because you are hallucinating it: there is nothing that instantiates
the visual features of a real red cube. Can we apply the same
reasoning to audition in order to claim that the premise is false
concerning auditory appearances too? When hearing a sound in S2, you
do not hallucinate the sound of a collision since you can perfectly
hear a sound without that there is a collision, as when listening to
music played by loudspeakers. Therefore, there is still something that
is the bearer of auditory qualities that you hear in S2 which can be
produced, for example, by loudspeakers and you are clearly not having
a hallucination (Nudds 2018: 56). That is to say that while it seems
that, in the visual case, we hallucinate, in the auditory case we are
clearly hearing a sound, and we can conclude that the premise is true
in audition. Nudds' conclusion can be challenged by the event
view since one can say that an environmental event is still present in
S2, that is, the event involved in the mechanics responsible for the
functioning of the loudspeaker. Therefore, the premise is false in the
auditory case as well, but for a different reason: not because you are
hallucinating a sound, but because the loudspeaker case does not show
that you hear sound in the absence of an environmental event.



(2) Nudds (2018: 56) adds that the falsity of the existence premise in
the visual case can be showed also by imagining to see a hologram in
S4. If what you see when it seems to you that you see a red cube is a
hologram of a red cube--that is, you have the experience of
seeing something that is indistinguishable from seeing a real red
cube--you don't literally see the object, but you do not
hallucinate it as well. When seeing a hologram of a red cube, you see
something which is the bearer of visual qualities without that the
actual object having these visual features is present. Starting from
Martin's (2012) discussion of visual images, according to which
a hologram is the appearance of an object "in the absence of any
object which might possess it" (2012: 339), Nudds concludes that
a hologram presents the appearance of something that it does not
instantiate. Therefore, the existence premise is false not because you
literally see nothing in S4, as usually happens in hallucinations, but
because what you see is not the bearer of visual features; and yet it
is indistinguishable from a real red cube. Is there a similar case in
audition which can be used in order to show that the existence premise
is false? Given that auditory holograms do not seem to exist, namely,
"something that presents the acoustic appearance of a
sound-producing event, an appearance it does not itself
instantiate" (2018: 58), it is difficult to claim that the
existence premise is false in audition for the same reasons for which
it is false in vision; therefore, Nudds concludes that the existence
premise is true: environmental events are not the bearers of acoustic
features. This conclusion is based on the debatable notions of
auditory hologram and auditory "image". Is it really
legitimate to look for analogous auditory concepts for notions that
are authentically visual? Important questions that are triggered by
Nudds' argument are: how far we can go with the analogy between
vision and audition, and how admissible is to ground our reasoning on
the analogy between the two sensory modalities especially when dealing
with items so intrinsically visual, such as holograms and images?


### 3.3 The Dispositional View



There are yet other ways to construe sounds under the distal umbrella.
According to dispositional account of sounds, 



> 
> 
> sounds are dispositions of objects to vibrate in response to being
> stimulated. Sounds are perceived transiently, but they are not
> perceived as being transient and they are not in fact transient.
> (Kulvicki 2008: 2) 
> 
> 
> 



The account takes Pasnau's original insight that sounds be
considered as akin to colors in their being located features of
objects. Indeed, Kulvicki draws a set of analogies between sounds and
colors based on the assumption that colors are dispositions to reflect
light in a certain manner. The analogies include the fact that as
colors exist in the dark (being dispositions) sounds exist in the
vacuum, and that as light waves are a way to get knowledge of colors,
compression waves in a medium are a way to get knowledge of sounds. To
complete the analogy, as "colors give off light when stimulated
by light, objects in a medium give off compression waves when they are
thwacked" (2008: 4). More controversially, "Without
vibrating, objects have sounds, but these sounds cannot be
heard" (2008: 4). *Thwacking* is the key element in the
dispositional proposal. Thwacking *reveals* sounds. A good
thwack (an impulse that contains all relevant frequencies) is
considered to be to sounds what white light is to colors. White light
contains waves of all lengths in roughly the same proportion and thus
samples adequately the dispositions of the object to reflect some of
them. If you lit up a surface with a monochromatic laser beam at
500nm, the disposition the surface may have to reflect light of 600nm
will not be revealed. A good thwack makes the object resonate at all
frequencies and thus reveals the vibratory modes of an object by
stimulating it at the frequencies at which it responds better.



The impulse proposal solves an alleged disanalogy between color and
sound, i.e., the absence of a normative analogue of white light in the
case of sounds (O'Callaghan 2007). White light is normatively
significant for revealing colors; a good impulse is normatively
significant for revealing a sounding disposition.



Kulvicki's dispositional theory neatly accounts for some distal
intuitions about sounds. (Other intuitions, such as the idea that
sound have a loudness, are beyond the descriptive power of the theory,
that on that score considers loudness as a property not of the sound,
but of the thwack). In particular it highlights the importance of
action in bringing about auditory information about an object: most
objects sound because we deliberately impart a thwack on them, and in
many cases in which we want to know how an object sounds, we do impart
the thwack, and subtly modulate it. When we hear a sound we get
knowledge of a kind of resistance an object opposes to thwacking; it
is knowledge of an elastic disposition. The account explains the fact
that the more the object reacts, the more it is sonorous. And an
object--say, a guitar string--is "A sharp"
because at that frequency it responds optimally to thwacking.



Kulvicki's alleges that an analysis of the phenomenon of sound
constancy, modeled on an analogue to color constancy, militates in
favor of the dispositional view. Colors are notoriously resilient to
many changes of illumination, and even when incident light composition
is very distant from standard light, surfaces may be seen as having
their standard color. "The green grass looks green in the orange
light at dusk, but it looks like green grass illuminated oddly"
(Kulvicki 2008: 9). This is in sync with the likely function of
vision--to inform about distal, stable properties of surfaces.
Analogously, Kulvicki claims, "objects sound roughly the same
whether it is white noise [i.e., an impulse] or something reasonably
far from it that stimulates them" (2008: 9). Our ability to
recognize voices across a large variation of ways to produce them is a
case in point. In general, humans are able to identify sounds in terms
of their spectral slopes and spectral envelope patterns, which are
"fairly constant across changes in the fundamental frequency
produced by the vocal chords" (2008: 10). Now, it can be
objected that voices are but a part of the auditory world, and they
are the object of dedicated neural machinery. More generally, however,
sound constancy is exhibited in hearing objects of various sorts. 



> 
> 
> There is no obvious reason the auditory system should exhibit
> constancy for something like spectral slope or envelope pattern,
> unless the auditory system has the function of identifying stable
> properties of objects. (2008: 10) 
> 
> 
> 



Facts of auditory constancy thus help out the dispositional theory
insofar as the function of the auditory system is to find out whatever
stable property of the environment is heard as being indeed
constant.


#### Objections to the dispositional theory



We shall enlist two objections to the dispositional account.



A first problem with the dispositional account is that of specifying
what precisely the disposition in question is. An object's
disposition to vibrate at its natural frequencies does not exhaust the
possibilities. 



> 
> 
> When struck, an object vibrates in an odd but characteristic fashion
> for a brief time before it settles into vibrating at its natural
> frequencies, if it has any. Like natural frequencies, these attack
> patterns are relatively stable dispositions of objects to vibrate when
> thwacked. Similarly, objects' vibrations decay
> characteristically. Attacks and decays are stable dispositions of
> objects to vibrate when thwacked, just as natural frequencies of
> vibration are. (Kulvicki 2008: 14)
> 
> 
> 



Hence there are three dispositions (at least) here: a disposition to
react in the attack mode, a disposition to react in the decay mode, a
disposition to vibrate in a certain way. There are many more. For
instance, a disposition to respond by emitting a certain pattern of
waves when rubbed or when brushed; or when broken. Many are the
dispositions, and the dispositional account should endorse the idea
that many are the (possibly unheard) sounds here. Call this the
many-disposition problem.



Normativity half-solves the many-disposition problem. Some ways of
imparting energy to an object are more telling than others. By
contrast, light is the sole "thwacker" for colors (modulo
differences in intensity and light spectrum), but there are many
twhackers for eliciting the sonority of an object. The dispositional
theory of colors suffers from some variant of the many-disposition
problem. The color of many objects and stuff depends on their
temperature. At 1000 degC, iron glows. At [?]20 degC, water is
white.



A different problem for the dispositional theory is: What are those
individuals that we hear when the object sounds? The main problem a
dispositional account of sounds has to face is that even if we accept
that sounds are sound dispositions, there appear prima facie to exist,
on top of those dispositions, the individual, occurrent
sounds--those that last when the disposition is realized. (A
similar problem plagued Chisholm's account of events as
repeatable entities: as Davidson pointed out, any such account should
accommodate the problem of assigning a status to the single
occurrences of the repetitions, which cannot be themselves repeatable
items.) Indeed, as Kulvicki notes,"now and again one encounters
objects making sounds they do not have" (2008: 8); he dismisses
these encounters as rather exceptional, but no matter their
frequency--and radio listening provides a very common
example--the "sound made", as distinct from the
"sound had", must be accommodated by any theory of sounds.
Kulvicki addresses the problem in a general way, by distinguishing
between sounds as dispositions and the hearings of sounds. There are
no individual sounds, only episodes of hearing the dispositional
sounds. We do hear sounds, these are the dispositions, but the
impression that sounds last depends on the fact that our hearing
episodes last.



Kulvicki denies that this account entails an error theory because he
thinks that intuitions are not particularly telling about the
distinction between hearing as an individual event and hearing a
sound. However, a threefold distinction should apply here. Grant the
dispositional sound. Grant hearing episodes. Now, the duration of a
hearing episode is different from the duration of an occurrent sound.
You set a tuning fork in motion. It vibrates for thirty seconds. But
then, after ten seconds, you get bored and block your ears with your
hand. The duration of your hearing is ten seconds. But the sound is
still there, for another twenty seconds. Generally speaking, unheard
sounds are accounted for in the dispositional theory only as
unrealized dispositions. Occurrent unheard sounds are invisible to the
dispositional account.



Kulvicki answers this objection by saying that this phenomenon is
consistent with the dispositional view (2014: 218). In order to have
sounds, it is required that the dispositions of an object to vibrate
in a certain way are realized, that these dispositions generate waves
in a medium, and that ears can detect these waves. Occurrent unheard
sounds produced when you block your ears and do not hear the tuning
fork vibrating for thirty seconds are not a problem simply because
they are not sounds. For the dispositional view "sounds are not
occurrent anythings: they are qualities" (2014: 218). But the
questions that naturally arise and need to be answered are: if the
unheard dispositions are not sounds, what are they? Moreover,
imagining that when I am still blocking my ears with my hand, someone
else is there listening to the tuning fork, would she be listening to
sounds? What are the items she would be listening to?



Another critical point of the dispositional view is that it does not
take into account the intuitive fact that sounds are heard as
unfolding over time and as having a duration, which is a clear sign of
their being an event. Kulvicki (2014: 211) discusses this by
elaborating on the plausibility of the argument of "perceptual
seeming" that he attributes to the people who claim that sounds
are events. The argument is based on the commonsensical idea for which
if sound *appears* to have a duration, it is because it
actually *has* a duration. This argument rests on three
assumptions: 


1. our experience of sounds can last a certain amount of time;
2. we usually say we hear happenings, such as the slamming of a door
or the falling of a tree, which we commonly refer to as
"events";
3. the events we hear have a duration that seems to coincide with
the duration of our experience of them.



For Kulvicki, even though the concurrence of these three assumptions
does not imply that sounds have durations, the claim that sounds have
a duration is still the *best explanation* of the three
uncontroversial claims. Therefore, even though, he does not propose a
way to completely undermine this argument, he suggests a way to weaken
it at least. The dispositional view can account for the third auditory
intuition--for which the time the events we hear take to occur is
often coincident with the duration of the related auditory
experience--emphasizing the role of mechanical stimulants. If we
imagine the circumstance of a "long-lasting, broad-spectrum
mechanical stimulant" (2014: 214) which thwacks the sounding
object in a stable vibratory disposition, it is not surprising that we
hear events for about as long as we hear sounds. Kulvicki himself
recognizes that this is not a conclusive way of excluding that sounds
have durations, but yet it is a way of weakening this claim.



Recently Kulvicki (2017: 91) has proposed a more inclusive view of
what sounds are. He admits that identifying sounds with the mere
vibratory dispositions of objects does not seem to capture the full
range of the auditory experience. Therefore, among sounds he includes
also aspects of events and the contexts in which those aspects are
heard, and distinguishes between non-perspectival and perspectival
qualities. The former are the dispositions of objects to vibrate in
response to being mechanically stimulated but also happenings, and the
second are "abstractions over features of objects, events, and
environs" (2017: 87). Both qualities are taken to be sounds,
which are a "mongrel" category. Kulvicki explains that the
perspectival qualities are "abstraction over intrinsic and
relational features of ordinary objects, environments, and range
events in which they participate" (2017: 90). That is,
concerning some aspects things sound in a way and, concerning other
aspects, they sound differently, depending on the perspective. When we
imitate the voice of someone, the reproduction of her voice is similar
to the original in some respects but is different in others. Within
Kulvicki's view, the worry is that sounds seem to be different
kinds of things, very distant and often in opposition with each other
(features of objects but also happenings, perspectival properties but
also non-perspectival qualities). Rather than claiming that these are
different ways of characterizing sounds, Kulvicki is exhaustively
telling us the different things we can hear, without explaining in
full what sounds are.


## 4. Aspatial Theories



We divided up existing accounts of sounds according to the spatial
location they assign to sounds. However, there are aspatial theories
of sounds as well. Aspatial theories deny either (i) that sounds are
intrinsically spatial, or (ii) that auditory perception is
intrinsically spatial. Arguably, claim (i) implies claim (ii), but the
converse is not true, which leaves room for an interesting aspatial
theory of auditory perception which nevertheless acknowledges that
sounds have some spatial locations.


### 4.1 Aspatial Sounds



We have seen the use of phenomenological arguments against both medial
and proximal theories of sound. To sum them up, one may claim that,
first, auditory experience has a spatial content whereby sounds seem
to be located in egocentric space (to the left, above, in front of us,
etc.). Second, unless one subscribes to an error theory of auditory
experience, sounds are where they are (normally) heard to be, namely
at their sources.



Before presenting a-spatial theories, let us conclude the discussion
on the spatial theories of sound by adding that they all share the
assumptions that reflections on the spatiality of audition are crucial
in order to tackle issues on the metaphysics of sound--that is,
we can say what sounds *are* when we know *where* they
are located (Di Bona 2019). Moreover, considerations on the spatiality
of audition and sounds are also important to understand the
segregation of auditory streams--which constitute the auditory
landscape--and the experience of some musical compositions
(2019). Finally--despite the remarkable difference between the
spatiality of vision and the spatiality of audition due to the fact
that, in audition, we perceive where sources are, the space between us
and the sources (O'Callaghan 2010b) and the space between the
sources, whereas, in vision, we perceive also where objects are
potentially to be seen (Nudds 2009)--spatial cues can also enter
the auditory content and provide info on the volume of empty space,
especially when derived from reverberations produced in a specific
closed space (Young 2017).


 But are sounds really located in space? There is in the literature
a strong non-locational view of sounds. Strawson has made the
plausibility of a thought-experiment of a purely auditory world rest
upon the tenet of an intrinsic non-spatiality of sounds. (Philosophers
and psychologists such as Lotze (1841 [1884: Ch. 6, 123-6]),
Binet (1905: Ch. 3), Heymans (1911 [1905]: Ch. 1), Stumpf (1883-1890: Vol. 1,
29), Wellek (1934), Revesz (1946), Ihde (1976: Ch. 6),
Evans (1980 [1986: 248 ff.]), have investigated the phenomenology of
auditory space and suggested the possibility of a purely auditory
world.) Strawson (1959: 65-66) thus wrote: 



> 
> 
> Sounds...have no intrinsic spatial characteristics: such
> expressions as "to the left of", "spatially
> above", "nearer", "farther" have no
> intrinsically auditory significance (...). A purely auditory
> concept of space...is an impossibility. The fact that, with the
> variegated types of sense-experience which we in fact have, we can, as
> we say, "on the strength of hearing alone" assign
> directions and distances to sounds, and things that emit or cause
> them, counts against this not at all. For this fact is sufficiently
> explained by the existence of correlations between the variations of
> which sound is intrinsically capable and other non-auditory features
> of sense-experience.
> 
> 
> 



Strawson designed his thought-experiment in the context of an analysis
of the Kantian claim that the notion of there being objective entities
(entities which do not depend on our perception of them) involves the
notion of space: 



> 
> 
> [t]he question we are to consider, then, is this: Could a being whose
> experience was purely auditory have a conceptual scheme which provided
> for objective particulars? (Strawson 1959: 66) 
> 
> 
> 



Thus, he imagined a character (later on called "Hero" by
Evans 1980) who has only non-spatial auditory experiences. Hero
perceives sounds, but he does not perceive them to be located in
physical space. What Strawson tried to show is that Hero needs an
"analogue" to the notion of space in order to
"locate" sounds when they are not actually heard. This
analogue is provided by what Strawson calls a
"master-sound", namely a constant sound varying in pitch.
Any particular sound is heard against the background of the
master-sound. Thanks to the master-sound, Hero can distinguish between
experiencing the same particular sound again (when its
"location" as provided by the master-sound is the same),
and experiencing successively two particular sounds of the same type
(when they have different "locations" on the master-sound
map). Evans (1980) questioned the claim that the master-sound could
play the role of physical space in grounding the notion of objective
particulars; see also Strawson's (1980) reply to Evans.



In evaluating Strawson's thought-experiment, we should
distinguish the claim that there can be non-spatial auditory
experiences from the claim that there can be a world populated only
with sounds. Strawson's thought-experiment justifies the former
claim, but it does not obviously lead to the latter. One cannot infer
from the fact that we can perceptually represent a sound without
representing its location, that we can perceptually represent a
non-located sound.


### 4.2 Aspatial Auditory Perception



It is possible to argue that auditory perception is not intrinsically
spatial independently of a commitment to the claim that sounds do not
have spatial locations. This is O'Shaughnessy's view, who
writes that 



> 
> 
> while we have the auditory experience of hearing that a sound comes
> from p, we do not have any experience that it is here where it now
> sounds...And this is so for a very interesting reason: namely,
> that we absolutely never immediately perceive sounds to be at any
> place. (2000: 446) 
> 
> 
> 



However, O'Shaughnessy does not draw the conclusion that sounds
have no spatial locations. On the contrary, as we have seen, he
defends a proximal account of the location of sounds, according to
which sounds are where hearers, rather than sources, are (2009).



O'Shaughnessy would not be impressed by allegedly
phenomenological arguments according to which one normally hears
sounds as located at their sources. One may still have the feeling
that his sophisticated version of proximal theories does not locate
sounds where an untutored description of what is perceived suggests
they are. As a consequence, it appears to be another massive error
theory of auditory perception.


### 4.3 Sounds as Pure Events



Scruton (2009a, 2009b; see also his 1997) proposes a non-physicalist
account of sounds. He is impressed by the fact that when we hear
sounds as music we (can) hear them as events detached from their
physical causes. He then suggests that sounds are "pure
events", things that happen but which don't happen to
anything, and that they are "secondary objects", entities
whose nature is bound up with the way we perceive them.



One way of reconciling Scruton's interesting suggestions with a
physicalist account of sounds is to draw a distinction (which of
course should be properly developed) between the ontology we need to
account for our ecological ability to hear sounds in our natural
environment and the ontology we need to account for our (at least
partly acquired) ability to hear sounds as music. Eventually, the
ontology of sounds as music, which Scruton wants to focus on, might be
quite different from the ontology of natural sounds, which can still
be of the physicalist kind.


## 5. Conclusion



We have suggested that a fruitful way to classify the various accounts
of sounds that have been given in the literature is in terms of their
spatial locations. If the sounds we hear have spatial locations, they
can be thought to be located either where the material sources are
(distal theories), or where the hearers are (proximal theories), or
somewhere in between (medial theories). It has also been denied that
sounds have any spatial locations, which gives rise to a fourth class
of theories, aspatial theories. All these theories have interestingly
different phenomenological, epistemological and metaphysical
implications.