Listener sensitivity to spectral slope attributes
Jody E. Kreiman, Bruce R. Gerratt · The Journal of the Acoustical Society of America · 2007
Researchers have long known that the shape of the vocal source spectrum is an important determinant of vocal quality, but details regarding the perceptual importance of individual spectral features remain unclear. This study provides preliminary evidence about the perceptual importance of four acoustic source features: H1-H2 and the spectral slopes from 1.52 kHz, from 24 kHz, and above 4 kHz. Vowel stimuli were synthesized by varying each spectral parameter in steps. Because the perceptual salience of source parameters depends on F0 and on the inharmonic source spectrum, different series were created for a male and a female speaker, and for a source with little versus a large amount of inharmonic energy. Listeners heard all possible pairs of voices within each series and were asked whether stimuli were the same or different. We hypothesize 1) that listeners sensitivity to H1-H2 will greatly exceed their sensitivity to other parameters; and 2) that listeners sensitivity to H1-H2 and the slope of the spectrum from 1.52 kHz will be independent of noise, but that sensitivity to changes in the spectral shape above 2 kHz will depend on the presence of noise excitation in the voice.