In linguistics, prosody () is concerned with elements of speech that are not individual phonetic segments (vowels and consonants) but are properties of syllables and larger units of speech, including linguistic functions such as intonation, stress, and rhythm. Such elements are known as suprasegmentals. Prosody may reflect features of the speaker or the utterance: their emotional state; the form of utterance (statement, question, or command); the presence of irony or sarcasm; emphasis, contrast, and focus. It may reflect elements of language not encoded by grammar or choice of vocabulary. Attributes of prosody In the study of prosodic aspects of speech, it is usual to distinguish between auditory measures (subjective impressions produced in the mind of the listener) and objective measures (physical properties of the sound wave and physiological characteristics of articulation that may be measured objectively). Auditory (subjective) and objective (acoustic and articulatory) measures of prosody do not correspond in a linear way. Most studies of prosody have been based on auditory analysis using auditory scales. There is no agreed number of prosodic variables. In auditory terms, the major variables are: the pitch of the voice (varying between low and high) length of sounds (varying between short and long) loudness, or prominence (varying between soft and loud) timbre or phonatory quality (quality of sound) In acoustic terms, these correspond reasonably closely to: fundamental frequency (measured in hertz, or cycles per second) duration (measured in time units such as milliseconds or seconds) intensity, or sound pressure level (measured in decibels) spectral characteristics (distribution of energy at different parts of the audible frequency range) Different combinations of these variables are exploited in the linguistic functions of intonation and stress, as well as other prosodic features such as rhythm and tempo. Additional prosodic variables have been studied, including voice quality and pausing. The behavior of the prosodic variables can be studied either as contours across the prosodic unit or by the behavior of boundaries. Phonology Prosodic features are said to be suprasegmental, since they are properties of units of speech larger than the individual segment (though exceptionally it may happen that a single segment may constitute a syllable, and thus even a whole utterance, e.g. "Ah!"). It is necessary to distinguish between the personal, background characteristics that belong to an individual's voice (for example, their habitual pitch range) and the independently variable prosodic features that are used contrastively to communicate meaning (for example,