Acoustical Study of Isoparametric Tones in the Female Chest and Middle Registers in Singing

Abstract

Isoparametric tones (tones of the same fundamental frequency, sound level, and phonemic category in different registers) were studied in order to specify acoustic differences between the female chest and middle registers in singing. Within the same register, marked similarities were found from subject to subject in the distribution of energy among partials. Conversely, marked differences were found between registers. For a given pair of isoparametric tones, the chest register is characterized by greater energy in the higher partials while the middle register has a stronger fundamental. Characteristic of the sonagraphic portrayals of the transition between registers is a frequency perturbation and especially a break in the continuity of the vibrato. These findings would seem to support the theory that it is primarily the waveform of the source (vocal folds) that changes when a change is made from chest to middle register in the female voice in singing. [This investigation was supported in part by the National Institutes of Health under whose auspices the author is a postdoctoral fellow at Stanford University.]