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.
Taking advantage of the extended dynamic range of digital analysis of voice the H-Index represents the first proposed acoustical measure of glottal efficiency. "Hi" /hai/ was chosen to evaluate glottal efficiency since it provides an excellent test of glottal transformation from voiceless to voiced sound energy, the upper vocal tract having a neutral effect. Fifteen individuals with normal voices and 30 patients with hoarse voices were asked to say "hi." The power ratio of /h/ to /a/ was calculated from peak power of each measure from the power envelope. Voice quality had a highly significant effect on measured values (P < .001). A high degree of correlation (P < .001) was found with the AC/DC ratio, a standard aerodynamic measure of glottal efficiency. The results indicate that the H-Index represents an excellent measure of glottal efficiency, obviating the need of invasive techniques or expensive, highly specialized equipment.
The degree of turbulent noise in the breathy voice of 25 patients with incomplete glottal closure was determined by PARCOR (PARtial autoCORrelation) analysis. From 10,000 acoustic data points, 44 PARCOR coefficients were calculated to form the residue wave which is representative of the glottal source. The power difference between the residue wave and the original acoustic wave was calculated in order to define a new measurement of acoustic power termed the turbulent noise ratio (TNR). The 25 patients were studied before and after Isshiki thyroplasty type I (IttI). The TNR became smaller in 24 of these patients following IttI, and corresponded closely with acoustic (Fukazawa's Br-Index), aerodynamic (Isshiki's AC/DC ratio), mean airflow rate during phonation, and videolaryngostroboscopic findings. Data affirm that the TNR accurately reflects the degree of turbulent noise at the glottal source.
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