Effects of subglottal pressure variation on professional baritone singers' voice sources

Five professional operatic baritone singers' voice-source characteristics were analyzed by means of inverse filtering of the flow signal as captured by a flow mask. The subjects sang a long sustained diminuendo, from loudest to softest, three times on the vowels a:] and ae:] at fundamental frequencies representing 25%, 50%, and 75% of their total pitch range as measured in semitones. During the diminuendos, they repeatedly inserted the consonant p] so that associated subglottal pressures could be estimated from the oral pressure during the p-occlusions. Pooling the three takes of each condition, ten subglottal pressures, equidistantly spaced between highest and lowest, were selected for analysis. Sound-pressure levels (SPL), peak-to-peak glottal airflow, maximum flow declination rate, closed quotient, glottal dc flow, and the level difference between the two lowest partials of the source spectrum (H1-H2) were determined. All parameters except the glottal dc flow showed a systematic variation with subglottal pressure or the fractional excess pressure over threshold. The results are given in terms of equations representing the average across subjects for the relation between subglottal pressure and each of the mentioned voice-source parameters.