Recent experiments have provided evidence for an auditory locus of selective adaptation effects. The present experiment further tests this theory. A [pa]-[ka] series was constructed. The burst frication from the [ka] syllable was added to the vowels [u] and [i]. Subjects identified these syllables as [tu] and [pi]. These three syllables contained physically identical bursts but were identified by subjects as stops with three different places of articulation. The [pa], [ka], [tu], and [pi] syllables were used as adaptors on the [pa]-[ka] test series. The [ka], [tu], and [pi] syllables, which contained identical bursts, produced similar boundary shifts. The spectrally different [pa], although sharing its initial phoneme with [pi], produced an opposite shift. These results support an auditory locus for adaptation with little or no phonetic or linguistic influence. In a pairedcomparison procedure, [pa], [ka], [pi], and [tu] were used as exemplars. Both the [pa] and [pi] syllables produced fewer [p] responses to an ambiguous test item, whereas [ka] had the opposite effect of producing more [p] responses. The phonetic quality of the exemplar appears to have been the primary determinant of its effects in the paired-comparison procedure. Together, these results support a two-stage model of speech perception, in which neither of these stages are vowel contingent.