A Study of Subharmonics in Connected Speech Material

Subharmonics are often observed in running speech spectrograms that are difficult to quantify. This study investigates the relationship between rough voice quality and the presence—and amount—of subharmonics in connected speech material in a group of 35 male and 35 female speakers with voice pathology. Spectrum analysis was undertaken in 145 pathologic voices, of which 77 had subharmonics in connected speech. Only 34% of 70 subjects under investigation developed subharmonics in both connected speech and sustained phonations. All voices were judged as perceptually rough. The results of this study indicate that male and female voices with subharmonics do not differ in examined acoustic characteristics except for the modal fundamental frequency (F0). A small but significant difference in roughness scores between genders seems to be caused by the confounding perception of factors not related to acoustic measurements of F0 and number of subharmonics. The degree of roughness has a significant relationship with the irregularity index, percentage of low F0 estimates, and, to a lesser extent, power of subharmonics.