High-frequency power ratio of breathy voice.

Digital technological advances have made detailed voice analysis possible. This report proposes, with the use of such equipment, a new method of quantifying differences in the high-frequency content of normal and breathy voices. The high-frequency power ratio, a ratio of high-frequency power versus total power, was calculated as the lower limit of the high-frequency range (Fc) and varied from 1 to 10 kHz. The high-frequency power ratio values of two groups, 16 normal and 24 breathy voice individuals, were then compared. Three breathy individuals were also studied after type I thyroplasty. High-frequency power ratio values measured at an Fc of 6 kHz significantly separated normal from breathy voices. The specifications provided are appropriate for both the commercial voice lab and for clinical resources. Furthermore, a high-frequency power ratio (6 kHz) is a useful tool for the evaluation of phonosurgery.