Some differences between phonetic and auditory modes of perception

When third-formant transitions are appropriately incorporated into an acoustic syllable, they provide critical support for the phonetic percepts we call [d] and [g], but when presented in isolation they are perceived as time-varying ‘chirps’. In the present experiment, both modes of perception were made available simultaneously by presenting the third-format transitions to one ear and the remainder of the acoustic syllable to the other. On the speech side of this duplex percept, where the transitions supported the perception of stop-vowel syllables, perception was categorical and influenced by the presence of a preposed [al] or [ar]. On the nonspeech side, where the same transitions were heard as ‘chirps’, perception was continuous and free of influence from the preposed syllables. As both differences occurred under conditions in which the acoustic input was constant, we should suppose that they reflect the different properties of auditory and phonetic modes of perception.