Speech perception is hearing sounds, not tongues

Three types of evidence are reviewed which cast doubt on claims that recovery of the speaker's articulations is an inherent part of speech perception: (a) Phonological data (e.g., universal tendencies of languages' segment inventories, phonotactic patterns, sound changes, etc.) show unmistakably that the acoustic-auditory properties of speech sounds, not their articulations, are the primary determinant of their behavior. (b) Infants and various nonhuman species can differentiate certain sound contrasts in human speech even though it is highly unlikely that they can deduce the vocal tract movements generating the sounds. (c) Humans can differentiate many nonspeech sounds almost as complex as speech, e.g., music, machine noises, as well as bird and monkey vocalizations, where there is little or no possibility of recovering the mechanisms producing the sounds.