Discriminant analysis of the acoustics of seven English voiceless fricatives

Abstract

The analysis of fricatives has typically been either acoustic (by spectroscopy and analysis‐by‐synthesis) or perceptual (by multi‐dimensional scaling of responses to natural stimuli and bivariate analysis of responses to specially prepared stimuli). While these contribute to our knowledge, there are too many possible acoustic cues within the speech signal to be accounted for in an economical way. Further, of the English voiceless fricatives, only [f θ s ∫] have been studied extensively; the three fricative‐like sounds [h ʍç], occurring at a systematic phonetic level in many English dialects, have been largely neglected. The present study used multiple discriminant analysis to find the most effective acoustic cues for discriminating and characterizing phonologically all seven English voiceless fricatives. Acoustic information was extracted digitally using several techniques whose relative effectiveness was then compared. The most successful measures were the quartiles of spectral energy distribution, expressed in mels; VOT; and the peak amplitude of the fricative relative to the peak of the neighboring vowels. Three discriminant functions were found to account for 98.5% of the variance; posterior classification was successful in 90% of the samples.