Vocal register effects on vowel spectral noise and roughness: findings for adult males.

This study was the second in a series designed to investigate the effects of vocal register (vocal, fry, modal, and falsetto) on the perceived roughness and spectral noise level of isolated test vowels. The first study (reported previously) was concerned with such effects on the phonations of adult females; in this study the phonations of adult males were investigated. Each of 15 male subjects produced at a controlled intensity each of two test vowels (/u/ and /ae/) in each of three vocal registers. Eleven listeners subsequently rated the test samples for roughness on a 5-point equal-appearing intervals scale. The criterion measure of roughness for each sample was the median of listener ratings (MRR). Each sample was also analyzed to produce its 3-Hz bandwidth acoustic spectrum from which measures of vowel spectral noise were obtained. The criterion measure of spectral noise level (SNL) for each test sample was the mean of 25 measures taken in the frequency range from 100 to 2600 Hz. The major finding was that the MRR and SNL for productions of both test vowels diminished significantly across vocal registers; i.e., from fry, to modal, to falsetto. In general, the present findings for males appeared consistent with those we reported earlier for phonations by adult females.