Perceptual interaction of the harmonic source and noise in voice

Abstract

Although the amount of inharmonic energy (noise) present in a human voice is an important determinant of vocal quality, little is known about the perceptual interaction between harmonic and inharmonic aspects of the voice source. This paper reports three experiments investigating this issue. Results indicate that perception of the harmonic slope and of noise levels are both influenced by complex interactions between the spectral shape and relative levels of harmonic and noise energy in the voice source. Just-noticeable differences (JNDs) for the noise-to-harmonics ratio (NHR) varied significantly with the NHR and harmonic spectral slope, but NHR had no effect on JNDs for NHR when harmonic slopes were steepest, and harmonic slope had no effect when NHRs were highest. Perception of changes in the harmonic source slope depended on NHR and on the harmonic source slope: JNDs increased when spectra rolled off steeply, with this effect in turn depending on NHR. Finally, all effects were modulated by the shape of the noise spectrum. It thus appears that, beyond masking, understanding perception of individual parameters requires knowledge of the acoustic context in which they function, consistent with the view that voices are integral patterns that resist decomposition.

Voice quality and tone identification in White Hmong

“…The linguistics literature has typically focused on harmonic attributes of breathiness (e.g., Fischer-Jïrgensen, 1967;Bickley, 1982;Esposito, 2010a), whereas the voice literature usually focuses on the role of noise (e.g., Hillenbrand et al, 1994;Shrivastav and Sapienza, 2006). The results of this study reinforce that both the harmonic and inharmonic components of the voice source, as well as their interaction, must be important in the perception of phonation, and thus that context is important in the interpretation of acoustic cues to voice quality (Kreiman and Gerratt, 2012).…”

“…Of course, we are not claiming that noise is not a cue to breathy voice in White Hmong. It is extremely likely that listeners would attend to noise if it were strong, given the known role of noise in English listeners' perception of breathiness and its interaction with spectral slope (Klatt and Klatt, 1990;Kreiman and Gerratt, 2005;Shrivastav and Sapienza, 2006;Kreiman and Gerratt, 2012) and the measured differences in harmonics-to-noise ratio between the breathy and modal tones in Hmong (Garellek, 2012). However, the current study indicates that when the noise level is only intermediate, spectral slope variation alone can control the rate of breathy responses.…”

“…The source shape of this base form was then modified according to the four harmonic-amplitude parameters of the source model described in the Introduction (Kreiman et al, 2007(Kreiman et al, , 2011Kreiman and Gerratt, 2012): H1-H2, H2-H4, H4-2 kHz (the harmonic closest to 2000 Hz), and 2 kHz-5 kHz (the final harmonic in the source model, closest to 5000 Hz). 4 For every stimulus file, the amplitudes of all harmonics were adjusted to the slopes of these components, as shown in Fig.…”

“…When spectral noise is added to the harmonic-amplitude parameters, a fiveparameter model of the voice source spectrum is obtained. Here we focus on the perception of just the harmonic amplitudes, leaving aside the important question of how they interact perceptually with spectral noise in the perception of voice quality [though see Kreiman and Gerratt (2005), Shrivastav and Sapienza (2006), and Kreiman and Gerratt (2012) for initial results on that topic]. This simple model might suffice to describe cross-speaker voice differences.…”

Acoustic and perceptual effects of changes in body layer stiffness in symmetric and asymmetric vocal fold models

“…The present study further showed that when vocal folds are symmetrically stiff, as in series I, the major acoustic effect of varying body stiffness was the extent to which the folds excited high-order harmonics in the produced sound spectrum as demonstrated by the strong correlations between body stiffness and the number of harmonics above the noise baseline in the spectrum for that series. Because listeners are perceptually sensitive to changes in the harmonic structure and slopes of harmonic spectra (Kreiman and Gerratt, 2012), the number of harmonics became the single most important acoustic measure that linked physiology (body stiffness) to perception in the symmetric conditions in series I. Although contraction of the cricothyroid muscle also plays a role, the TA muscle is the primary regulator of body layer stiffness (Hirano, 1974).…”