Acoustic Correlates of Vocal Quality

Abstract

We have investigated the relationship between various voice qualities and several acoustic measures made from the vowel /i/ phonated by subjects with normal voices and patients with vocal disorders. Among the patients (pathological voices), five qualities were investigated: overall severity, hoarseness, breathiness, roughness, and vocal fry. Six acoustic measures were examined. With one exception, all measures were extracted from the residue signal obtained by inverse filtering the speech signal using the linear predictive coding (LPC) technique. A formal listening test was implemented to rate each pathological voice for each vocal quality. A formal listening test also rated overall excellence of the normal voices. A scale of 1–7 was used. Multiple linear regression analysis between the results of the listening test and the various acoustic measures was used with the prediction sums of squares (PRESS) as the selection criteria. Useful prediction equations of order two or less were obtained relating certain acoustic measures and the ratings of pathological voices for each of the five qualities. The two most useful parameters for predicting vocal quality were the Pitch Amplitude (PA) and the Harmonics-to-Noise Ratio (HNR). No acoustic measure could rank the normal voices.

The perceptual structure of pathologic voice quality

“…For example, many believe that jitter has consistent perceptual correlates ͑roughness is the most frequently mentioned; Gerratt and Kreiman, 1995͒, and thus that it is a good measure of vocal quality. However, correlations between measures of jitter and perceived roughness have ranged from Ϫ0.01 ͑Es-kenazi et al, 1990͒ to 0.98 ͑Heiberger and Horii, 1982͒; and jitter has been significantly ͑if not always highly͒ associated with many qualities, including grade/severity of pathology ͑Askenfelt and Wolfe andRatusnik, 1988͒, breathiness ͑Hirano et al, 1988;Eskenazi et al, 1990;Feijoo andHernandez, 1990͒, hoarseness ͑Haji et al, 1986;Horiguchi et al, 1987͒, andstrain ͑Arends et al, 1990͒.…”

Voice processing in human and non-human primates

“…In addition to this quasi-periodic component, the source contains some proportion of inharmonicity, such as temporal irregularities in vocal fold vibration (contributing to the 'rough' quality of voice) or noise caused by aerodynamic turbulences (contributing to the 'breathy' quality of voice; the source exclusively consists of turbulent noise in the case of whispered speech). Besides the 'modal' register described above, humans as well as monkeys and apes are also able to use the larynx in different modes with varying degrees of nonlinearity, such as the 'falsetto' and the 'vocal fry' registers in humans (Eskenazi et al 1990). The sound emitted by the larynx is modified by the cavities and tissues located above the larynx (supralaryngeal vocal tract), which act as an acoustic filter relatively independent of the source characteristicsfor example, unlike in wind instruments (Fant 1960;Fitch 2003).…”

A model for the prediction of breathiness in vowels

“…These include measures of short-term perturbation (e.g., Eskenazi et al, 1990;Prosek et al, 1987;Martin et al, 1995), relative noise level (de Krom, 1993;Hirano et al, 1988), relative amplitude of the first harmonic (de Krom, 1994;Hillenbrand et al, 1994), spectral slope (Hammarberg et al, 1980), glottal source characteristics (Childers and Lee, 1991;Klatt and Klatt, 1990), and the relative amplitude of the cepstral peak (Hillenbrand et al, 1994). However, none of these measures has shown a consistent and high correlation with perceptual judgments of breathy voice quality when tested across multiple a) Author to whom correspondence should be addressed.…”