ACOUSTIC ANALYSIS OF VOICE MEAS- URES IN CHRONIC LARYNGITIS PATIENTS

Abstract

We aimed to analyse voice signals in 40 patients with chronic laryngitis elicited by exposure to chemical factors. We ex- amined 20 people with catarrhal chronic laryngitis (group 1), 20 people with subatrophic chronic laryngitis (group 2) and 15 healthy volunteers as controls. All subjects underwent acoustic examination of the voice signal using the software Praat V 4.2.1. We studied acoustic measures as follows: Jitter, Shimmer and NHR (noise-to-harmonics ratio). The analysis of the obtained data revealed statistically significant differ- ences in the average values of Jitter and Shimmer measures, as well as in the ratio of nonharmonic (noise) and harmonic component in the spectrum ( NHR) in patients with chronic laryngitis (groups 1 and 2) compared with controls. In group 1 (chronic catarrhal laryngitis), the average values of acoustic measures such as Jitter, Shimmer and NHR were as follows: Jitter - 0.92 ± 0.1%, Shimmer - 5.31 ± 0.5%, NHR - 0.078 ± 0.04. In group 2 (subatorophic laryngitis), the average values of acoustic measures were: Jitter - 0.67 ± 0.6%, Shimmer - 6.57 ± 0.7% and NHR - 0.028 ± 0.003. The obtained data indicate a pronounced instability of the voice in frequency and amplitude, a significant proportion of the noise component in the spectrum of the voice signal in the examined patients with chronic laryngitis exposed to chemical factors. The most pronounced alterations were found in patients with catarrhal chronic laryngitis. We conclude that the quantitative values of spectral analysis of the voice signal Jitter, Shimmer, NHR may serve as valuable criteria of the degree of voice impair- ment. This may be helpful in determining the effectiveness of rehabilitation measures.