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The generation of area functions from measurements of the sagittal section is an important step in the study of the relation between vocal tract geometry and speech acoustics. We present a new model to perform this transformation, inspired by the [alpha beta] model of Heinz & Stevens (1965). Our model is based on analysis of a vocal tract cast for large sagittal dimensions and for small sagittal dimensions on CT scans of the vocal tract constriction zones for the three cardinal vowels [i, a, u] of French. We extracted two sets of coefficients, appropriate for large and small sagittal dimensions respectively. We then compared the predictions of the model with those of other models from the literature. Finally, the usefulness of this dual coefficient procedure for the acoustic simulation of vowels was tested using sagittal sections generated by an acoustic model of the vocal tract.

Spectra of vowels were analyzed to determine whether differences exist between the spectral slope of vowels produced by tracheoesophageal (TE) speakers and normal speakers and, if so, to quantify such differences. The linear predictive autocorrelation method was used to calculate smoothed spectra and the spectra were normalized with respect to a low frequency component. Comparisons between normalized spectral energy within a selected high frequency range revealed that energy within this frequency range for vowels produced by TE speakers was significantly higher than that produced by normal speakers. A least-square distance matching procedure was used to quantify speaker group differences in the spectral slope of vowels. Average spectra of vowels produced by the normal speakers could be matched to average spectra of vowels produced by the TE speakers by decreasing the spectral slope of their vowels by 2-3 dB/octave.

In a listening experiment, speech samples obtained from a tracheosophageal speaker were judged for intelligibility and general quality by inexperienced and experienced listeners. The speaker produced the speech samples using finger occlusion of the stoma and using a tracheostoma valve. Results showed no significant differences in intelligibility of speech between occlusion conditions for single words, 5-word sentences, and 10-word sentenceds. Conversational intelligibility was judged to be adversely affected by the tracheostoma valve, though quality of speech was not. No significant differences were found between the judgments of inexperienced and experienced listeners.

With 8 men, two methods of alaryngeal speech production, tracheoesophageal and electrolaryngeal, were compared on perceptual and acoustic measures of speech intelligibility. Measures consistently identified the tracheoesophageal speech as superior to electrolaryngeal speech.