Whisper and Phonation: Aerodynamic Comparisons Across Adduction and Loudness

Whisper is known to be produced by different speakers differently, especially with respect to glottal configuration that influences glottal aerodynamics. Differences in whisper production and phonation types imply important linguistic information in many languages, are identified in vocal pathologies, are used to communicate mood and emotion, and are used in vocal performance.

The present study focused on investigating the aerodynamic differences between whisper and phonation at different loudness and adduction levels.

Three men and five women between 20 and 40 years of age participated in the study. Smooth syllable strings of the syllable /baep:/ were whispered and phonated at three different loudness levels (soft, medium, and loud) and three voice qualities (breathy, normal, and pressed). The voice qualities are associated with different adduction levels. This resulted in 18 treatment combinations (three adduction levels × three loudness levels × two sexes).

A regression analysis was performed using a PROC MIXED procedure with SAS statistical software. Under similar production conditions, subglottal pressure was significantly lower in whisper than in phonation in 10 of 18 combinations, mean glottal airflow was significantly higher in whisper than in phonation in 13 of 18 combinations, and flow resistance was significantly lower in whisper than in phonation in 14 of 18 combinations, with the female subjects demonstrating these trends more frequently than the male subjects do. Of importance, in general, compared with phonation under similar production conditions, whisper is not always accompanied by lower subglottal pressure and higher airflows.

Results from this study suggest that the typical finding of lower subglottal pressure, higher glottal airflow, and decreased flow resistance in whisper compared with phonation cannot be generalized to all individuals and depends on the "whisper type." The nine basic production conditions (three loudness levels and three adduction levels) resulted in data that may help explain the wide range of variation of whisper production reported in earlier studies.