Lorin Wilde
Res. Lab. of Electron., Dept. of Elec. Eng. and Comput. Sci., MIT, Rm. 36-547, Cambridge, MA 02139
Formant transitions provide context-dependent acoustic cues that can be interpreted in terms of the articulatory kinematics involved in moving from a consonant to a vowel. Formant frequencies were measured at identified acoustic landmarks for eight English fricatives preceding front, back, and back-rounded vowels. Formant onset times designated the point when the energy increased most rapidly and evidence of the first formant was first observed. Comparing the two-dimensional representation of F2xF3 onset frequencies along the voicing dimension showed the voiceless fricatives to be more dependent on vowel context. The onset frequencies for voiced fricatives reflect a more extreme supraglottal posture, while the voiceless fricative measures can be considered to be at a point closer to the vowel because voicing begins at a later time relative to the oral release gesture. Formant structure in the noise before the release, to the extent that it is visible in the consonantal interval prior to voicing onset, can provide additional place information for voiceless fricatives. Formant onset data are compared with measurements reported from investigations of place categorization of stop consonants. [Work supported by NIH.]