Musical illusions, absolute pitch, and other enigmas of sound perception.

Abstract

Several phenomena that were discovered by the author are described, and their implications for music and speech perception are explored. First described is an algorithm for producing circular scales from sequences of single tones, with each tone comprising a full harmonic series. Next discussed are illusions, such as the scale illusion and the glissando illusion, which occur when two streams of sound emanate simultaneously from different regions of space. In several such illusions, a perceptual reorganization occurs, so that a melody formed of tones in one pitch range appears to be coming from one region of space, and another melody, formed of tones in a different pitch range, appears to be coming from the opposite region. Next explored is an illusion in which a spoken phrase comes to be heard as sung rather than spoken, simply by repeating it several times over. Finally, absolute pitch is examined. Although this has been considered a rare faculty, it is shown that speakers of tone language have a very high prevalence of absolute pitch; it is argued that this is due to the association of pitches with meaningful words during the critical period for speech acquisition. The talk is accompanied by sound demonstrations.