An acoustic and Perceptual study of the voiceless portion of unvoiced stop consonants in American English

Abstract

An investigation of the acoustic properties of the voiceless portion of unvoiced stops was undertaken. Three male native speakers of American English were recorded reading a list of “CVd” words, in which the consonants /p,t,k/ appeared before the vowels /i,ɪ,e,E, ae,u,ᴜ,ʌ,o,a/. For each speech token, formant frequencies and amplitudes at 10‐ms intervals were estimated visually from hard copies of computer‐implemented DFT displays. It was found that for certain CV combinations the ratio of the average amplitude of F3 to that of F2 during the aspiration interval is considerably greater than the same ratio computed during the vowel. This finding could be explained either by greater losses through the open glottis for the second formant, or by the different excitation of the formants as a consequence of the source location and spectrum. In some cases, the presence of substantial energy in the region of F4 and F5 favors the latter explanation. These results raise questions concerning the perceptual importance of F2 in identifying place of articulation in voiceless stop consonants. Preliminary perceptual experiments are described in which this issue is explored. [Work supported by a grant from NINCDS.]An investigation of the acoustic properties of the voiceless portion of unvoiced stops was undertaken. Three male native speakers of American English were recorded reading a list of “CVd” words, in which the consonants /p,t,k/ appeared before the vowels /i,ɪ,e,E, ae,u,ᴜ,ʌ,o,a/. For each speech token, formant frequencies and amplitudes at 10‐ms intervals were estimated visually from hard copies of computer‐implemented DFT displays. It was found that for certain CV combinations the ratio of the average amplitude of F3 to that of F2 during the aspiration interval is considerably greater than the same ratio computed during the vowel. This finding could be explained either by greater losses through the open glottis for the second formant, or by the different excitation of the formants as a consequence of the source location and spectrum. In some cases, the presence of substantial energy in the region of F4 and F5 favors the latter explanation. These results raise questions concerning the perceptual importance ...