The effect of the spectral shape changes on voice perception
Mika Ito, Bruce R. Gerratt, Norma Antoñanzas-Barroso, Jody E. Kreiman · The Journal of the Acoustical Society of America · 2006
Researchers have long known that the shape of the vocal source spectrum is an important determinant of vocal quality, but the details regarding the importance of individual spectral features remains unclear. Previous research indicates four spectral features, H1-H2, the spectral slope above 4 kHz, the slope from 1.5–2 kHz, and the slope from 2–4 kHz, account for virtually all the variability in spectral shapes. The present study provides preliminary evidence about the perceptual importance of these four features. Four series of stimuli were synthesized for each spectral parameter, in which that parameter varied in small steps. Because the perceptual salience of source parameters depends on F0 and on the spectrum of the inharmonic part of the source, series differed in the sex of the speaker (male/female) and in the NSR (noise-free/very noisy). Listeners heard all possible pairs of voices within each series and were asked to determine whether stimuli were the same or different. We hypothesize that listeners sensitivity to H1-H2 and the slope of the spectrum from 1.5–2 kHz will be independent of noise, but that sensitivity to changes in the spectral shape above 2 kHz will depend on the amount of noise excitation present in the voice.