Variability in voice fundamental frequency of sustained vowels in speakers with sensorineural hearing loss

In a previous study, the low-frequency modulation extent (LFP) of the vocal fundamental frequency (F(0)) showed a significant increase in the presence of binaural noise masking for the healthy individuals. This study was to investigate the F(0) of subjects with sensorineural hearing loss (SNHL) using sustained phonations to explore the changes of F(0) modulations in SNHL. Twenty-three SNHL subjects and 14 age-matched subjects without hearing loss were enrolled in the study. Sustained vocalizations of vowel /a/ for more than 5 seconds were digitally recorded. The F(0) contour of each phonation was acquired using digital signal processing. The modulation extent at different frequencies was obtained using Fourier transformation of F(0) contour. The LFP of F(0) (<3Hz) was significantly greater for the SNHL subjects (P<0.001, independent samples t test). Although the correlation analysis was limited to the auditory-evoked brainstem response (ABR) thresholds because of their disagreement with the pure-tone thresholds in some subjects with functional hearing disorder, the correlation between LFP and ABR thresholds was significant (ρ=0.45, P=0.03, Spearman's correlation analysis). The LFPs of F(0) were significantly greater for the SNHL subjects and the changes of F(0) modulations could be detected using power spectral analysis of F(0). The method may be used for evaluation of audio-vocal feedback in SNHL.