Acoustic and perceptual study of phonetic integration in Spanish voicelessstops

The relationship between the acoustic content and the perceptual identifica tion of Spanish voiceless stops, /p/, /t/ and /k/, in word initial position , has been studied in two different conditions: (a) isolated plosive noise (C condition); (b) Plosive noise plus 51.2 ms of the following vowel (CV co ndition). The purpose of the study was to assess whether there was a clear correspondence between the perceptual identification made by listeners and the acoustic classification performed using a spectral representation combi ned with the duration, energy and zero-crossings of the plosive noise. The acoustic classification was represented by a distance profile, formed by th e acoustic distances between a given token and the three classes correspond ing to the three stops. The acoustic distances were defined as the a poster iori probabilities of membership in each class (APP scores). The perceptual identification was represented by a response profile, formed by the number of listeners' responses assigned to each of the classes for a given token. The correlation between the acoustic and perceptual distances increased fr om the C condition (overall correlation 0.81) to the CV condition (0.95), i ndicating that as the signal is more precisely defined from the perceptual point of view, the acoustic content is also less ambiguous, since both the perceptual and acoustic classifications improve in the CV condition. The be st correlations were achieved when the variables obtained in the temporal d omain (duration, energy and zero-crossings of the plosive noise) were inclu ded in the analysis. (C) 1999 Elsevier Science B.V. All rights reserved.