EFFECT OF RELATIVE AMPLITUDE OF FRICATION ON PERCEPTION OF PLACE OF ARTICULATION

The amplitude of frication relative to vowel onset amplitude in the F3 and F5 formant frequency regions was manipulated for the synthetic fr icative contrasts /s/-/integral/ and /s/-/theta/, respectively. The in fluence of this relative amplitude manipulation on listeners' percepti on of place of articulation was tested by (1) varying the duration of frication from 30 to 140 ms, (2) pairing the frication noise with diff erent vowels /i a u/, (3) placing formant transitions in conflict with relative amplitude, and (4) holding relative amplitude constant withi n a continuum while varying formant transitions and the amplitudes of spectral regions where relative amplitude was not manipulated. To dete rmine if listeners were using absolute spectral cues or relative ampli tude comparisons between frication and vowel for fricative identificat ion, the frication and vowel were separated by (1) presenting the fric ation in isolation, and (2) inserting a gap of silence between the fri cation and vowel. The results showed that relative amplitude was perce ived across vowel context and frication duration, and overrode context -dependent formant transition cues. The findings for temporal separati ons between the frication and vowel suggest that short-term memory pro cesses may dominate the mediation of the relative-amplitude comparison . However, the overall results indicate that relative amplitude is onl y a component of spectral prominence, which is comprised of a primary frication spectral peak and a secondary frication/vowel peak compariso n.