As the degree of judged hoarseness increases, the noise component of the spectrogram increases and replaces the harmonic structure. The relationship between these two components has been quantified as harmonics-to-noise (H/N) ratio. In this study, the contribution of cycle-to-cycle pitch perturbations (jitter) to the measured noise energy was analyzed. Moreover, the relationship between the acoustic parameters (H/N ratio and jitter) and the perceived abnormalities of hoarseness was studied.

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... t laryngologists rated their auditory impressions for G, R and B factors of87pathologic voices. G (Grade) represents the degree of hoarseness; R (Rough) refers to rumbling and heaviness; B (Breathy) is related to air leakage during phonation. Correlations of R factor with the H/N ratio or jitter were not so high as those of G or B factor with the H/N ratio (p<0.05). These findings suggest that the H/N ratio can be a quantitative index of B factor as well as of G factor, and that neither of the acoustic parameters are good indicators of R factor.