Absence or presence of preceding sound can change perceived phonetic identity

Participants were asked to categorize a series of syllables varying from /ga/ to /da/ presented in isolation or following /al/, /ar/, /a/, or filtered noise bands. Typical shifts in categorization were obtained for /al/ vs. /ar/ contexts as predicted by compensation for coarticulation, but the shift in response between isolated presentation and any of the context conditions was much larger, even when the context was broadband noise. These results suggest that the effect of the presence of any context sound is greater than the effect of the content of the context sounds.