Objective Evaluation Of Glottal Stops In Cleft Palate Speech Based On Spectral Moments

This study investigated acoustic features of glottal stops produced as substitutes for stop consonants by Mandarin speakers with cleft palate. As indices for overall energy distribution of the spectra, spectral moments were derived for the burst and the subsequent portion of stop consonants. The results show that stop consonants that were produced as glottal stops had less acoustic energy in the high-frequency range than typical stop productions. This finding might be due to the fact that the anterior cavity for glottal stops is usually larger than the one for typical stops. We also found that the spectral energy of glottal stops spread over a wider frequency range. Logistic regression was proposed as a pattern classifier and we obtained acceptable classification accuracy when selecting an optimal set of a few spectral coefficients as input factors. It appears that it is possible to objectively assess the presence of glottal stops with such spectral indices and classifier, and the assessment can be further automated if combining an automatic detection of stop bursts.