Measurements of subglottal resonances and their influence on vowel spectra

Abstract

Data collected from several speakers are being studied to estimate subglottal resonant frequencies. The utterances were ten vowels of American English embedded in the nonsense syllable /■hVd/. Sound-pressure signals were recorded by a microphone, and signals transduced by an accelerometer placed on the neck below the larynx were recorded simultaneously. In the accelerometer signal the subglottal resonances appear as well-defined spectral peaks, whereas in the microphone signal these resonances are manifested as small perturbations in the spectra. These perturbations are more pronounced for a speaker who, based on other spectral data, phonates with a significant glottal chink [H. M. Hanson and K. N. Stevens, Proc. ICPhS 95, Stockholm]. Comparison of spectra of the accelerometer and sound-pressure signals for two female speakers has resulted in estimated subglottal resonant frequencies of 625, 1540, and 2110 Hz. The bandwidths of the first subglottal resonances have also been estimated for the two speakers at 110 and 210 Hz, respectively. These results are in keeping with previous reports. Discontinuities in apparent formant movements have been observed in the vicinity of the estimated subglottal resonances, suggesting that resonances of the subglottal system can influence the acoustic characteristics of vowels. [Work supported by NIH Grant Nos. DC00205-02, DC00075.]