relate to the listeners' languages and dialects. The illusions also demonstrate the importance of memory, knowledge and expectations to how we perceive music and speech, and point to strong connections between the brain systems responsible for these two forms of communication. One set of illusions occur when two sequences of tones are presented over stereo headphones, such that when the right ear receives one sequence the left ear receives a different sequence. Using this procedure, Deutsch discovered striking illusions, as well as the octave illusion, the scale illusion, the chromatic illusion, the glissando illusion, and the cambiata illusion. She discovered that there are strong disagreements between listeners and how these illusions were perceived. These disagreements tend to occur between righthanders and lefthanders indicating that they reflect differences in brain organization. These illusions have implications for musical practice. For example, listening to music in concert halls may allow the audience to experience the same musical patterns in different ways. The illusions also demonstrate the existence of illusory conjunctions in hearing. Deutsch also produced illusions using sequences of tones that were defined in terms of pitch class (note name), but ambiguous in terms of which octave they are in (known as Shepard tones). In particular, she discovered the tritone paradox. Once again, this illusion gave the perception that differs substantially from one listener to another, but in this case, perceptual variations relate to the language or dialect spoken by the listener, indicating a relationship between music and speech. In addition, Deutsch discovered the Speech-to-Song Illusion. In this illusion, speech is made to be heard as a song, and this occurs without transforming the sounds in any way. Through simply repeating a phrase several times over, this illusion also points to a strong relationship between speech and music. Two further illusions discovered by Deutsch also show the importance of unconscious inference – our use of memory, beliefs and expectations – in perception of music and speech. One is called the mysterious melody illusion. Listeners are unable to identify a well-known melody when all its note names are correct, but the tones are placed randomly in different octaves. However, when listeners are told the identity of the melody, they are able to recognize it through stored knowledge. Another is the phantom words illusion. Using stereo loudspeakers, Deutsch presented repeating words and phrases that were composed of two syllables. The syllables alternated between the speakers