Harmonic emergence in formant zone of a sustained [a] as a parameter for evaluating hoarseness

In order to test the value of the harmonic emergence in formant zone of a sustained (a) as a parameter for evaluating hoarseness, a multifactorial acoustical investigation was performed in 10 normal and 22 dysphonic subjects. The parameters were: a subjective evaluation (7-degree-scale) of the extent of the hoarseness by 3 trained specialists the phonation quotient the 0-6 kHz/6-10 kHz energy ratio, computed on a long--time--average--spectrum from a reading of a phonetically selected text the harmonic emergence in the bandwidth of the two first formants of a sustained (a). The harmonic emergence in the formant zone of a sustained (a) seems to be an interesting and complementary parameter, with respect to the previously investigated 0-6 kHz/6-10 kHz energy ratio, for evaluating hoarseness. Both of these parameters demonstrate highly significant differences between normal and pathological voices. Moreover, they show a high degree of correlation both with the subjective evaluation of the severeness of the hoarseness and with the mean transglottic air flow during phonation. The 0-6 kHz/6-10 kHz energy ratio seems to discriminate better in cases of severe dysphonia, while harmonic emergence seems more suitable in milder hoarseness. Both spectral parameters are suitable for automatic analysis.