Acoustic analysis of three male voices of different quality

We know that formants typically differ between voice categories. It is reasonable to assume that differences exist also regarding the glottal voice source. The purpose of the present investigation was to map such voice source differences in representatives of three different male voice categories. Data are presented on subglottic pressure (as estimated from oral pressure during /p/-ccclusion) on the overall SPL as well as on the SPL of the "singer's formant", on the amplitude of the fundamental, and on the duration of the closed phase of the glottal vibratory cycle as measured from acoustic glottograns derived by menas of i'nverse filtering. The results show intersubject differences, the possible relevance of which to voice classification is discussed. Introduction Voice classification in singers has been subject of two previous investigationsbythe present authors (Cleveland, 1977; #gren & Sundberg, 1978). The results showed that in isolated, sustained vowels the pitch was the most important cue to perceptual voice classification. These results are similar to those obtained in a study on maleness or femaleness in voice timbre (Coleman, 1976). Vowel. formant frequencies have also been shown to be another cue to perceptual voice classificatio~l. Cleveland (1977) found that the higher the formant frequencies in a vowel frame, the more tenor-like the voice quality appeared to a group of trained listeners. From a study of two representatives of each of the alto and the tenor categol-ies, Agren and Sundberg (1978) inferred that the frequency of the fourth formant was probably typically higher in altos than in tenors. These findings are supported by data on the vocal tract length in singers (Jhnitriev & Kiselev, 1979). These results sulprt the corlclusial that formant frequencies and vocal tract morphology are significant to voice classification. Foth the Cleveland and the ffgren and Sundberg artlcles also considered the relevance of the voice source to perceptual voice classification. The results were limited to the finding that, within an individual singer, the source spectrum slope seemed to differ between low and high pitches. For example, it was observed that or1 pitch C3, which is a low pitch for a tenor and a high pitch for a bass, the tenor source spectrum slope was greater them tlle bass source spectrum. Since the aforementioned studies, a great deal of research relative to the voice source has been presented which has direct implications concerning our further understanding of the voice source cl~aracteristics also in professional sinqers (Rothenherg, 1981; Sundbery & Gauffin, 1379; Stm-rg & Gauffin, 19P1). These studies have improved our understanding of how characteristics in the voice source waveform are narlifested in the radiated vowel spectrum; therefore, it now seems approp# U n i v m i X y 06 Sou : thm C a A i d o h n i a , Lon A n g Q e ~ , CA, IJSA. riate to complement previous studies of voice categories with voice source data. The present investigation is a pilot study of voice source characteristics versus pitch in three subjects with differing voice classifications. The study includes data on subglottic pressure, sound pressure level. (SPL), amplitudes of the fundamental at~d of the singer's formant, and glottogram characteristics.