| Abstract | Objective:
This study investigated the effect of the variables adduction, pitch, loudness, and straight tones on fundamental frequency (fo) and airflow vibrato, and their inter-variable relationships.
Methods:
The subject (the third author) is a professional mezzo soprano. For each of three pitches (A3, F4, D5), she produced two loudness levels (piano, mf), two adduction levels (normal, hyperadduction), and two vibrato levels (normal, straight), for a total of 24 trials. Each trial was performed twice. Recordings were made in a sound treated booth using the Glottal Enterprises aerodynamic system, an electret microphone, and a Kay 6103 electroglottograph, and digitized with a DATAQ 16-bit system, and analyzed using Praat, BGSigplot, and Excel.
Results:
The results here are for the middle frequency F4. The effect of straight vibrato on airflow was to reduce the average airflow from 204 cm3/s to 122 cm3/s and reduce the airflow extent from 51 cm3/s to 13 cm3/s, suggesting that straight tone singing used greater adduction and retains some extent. The effect of hyperadduction was to reduce average airflow by 50%, with the effect of normal to straight tone being similar (96 cm3/s for normal vibrato vs 109 cm3/s for straight compared to the 204 cm3/s for normal vibrato and adduction). Airflow vibrato extent was interestingly little affected by hyperadduction (51 cm3/s normal vs 56 cm3/s hyperadduction), but similarly affected by straight tone (13 cm3/s normal adduction vs 13 cm3/s hyperadduction). Fundamental frequency (fo) vibrato extent was not affected by hyperadduction, but reduced by straight tone (35 Hz vs 4.5 Hz). Similar data will be reported for the other pitches and for the piano trials. In addition, airflow vibrato was found to be out of phase with fo vibrato for most trials that showed similar periodicity between fo and airflow vibrato.
Conclusions:
The unique aspect of this study regards airflow vibrato for hyperadducted and straight tone singing. Both reduce the average airflow and airflow extent, as well as the fo extent. A synchronized extension of the glottis may be a primary cause of airflow vibrato extent. Interestingly, the subject’s straight tone did not result in the absence of fo vibrato, but was reduced in amplitude sufficiently not to be heard (c. 1% of the fo).
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