Acoustic Perturbation Measures Improve with Increasing Vocal Intensity in Individuals With and Without Voice Disorders

Abstract

OBJECTIVE: In vocally healthy children and adults, speaking voice loudness differences can significantly confound acoustic perturbation measurements. This study examines the effects of voice sound pressure level (SPL) on jitter, shimmer, and harmonics-to-noise ratio (HNR) in adults with voice disorders and a control group with normal vocal status. STUDY DESIGN: This is a matched case-control study. METHODS: We assessed 58 adult female voice patients matched according to approximate age and occupation with 58 vocally healthy women. Diagnoses included vocal fold nodules (n = 39, 67.2%), polyps (n = 5, 8.6%), and muscle tension dysphonia (n = 14, 24.1%). All participants sustained the vowel /a/ at soft, comfortable, and loud phonation levels. Acoustic voice SPL, jitter, shimmer, and HNR were computed using Praat. The effects of loudness condition, voice SPL, pathology, differential diagnosis, age, and professional voice use level on acoustic perturbation measures were assessed using linear mixed models and Wilcoxon signed rank tests. RESULTS: In both patient and normative control groups, increasing voice SPL correlated significantly (P < 0.001) with decreased jitter and shimmer, and increased HNR. Voice pathology and differential diagnosis were not linked to systematically higher jitter and shimmer. HNR levels, however, were statistically higher in the patient group than in the control group at comfortable phonation levels. Professional voice use level had a significant effect (P < 0.05) on jitter, shimmer, and HNR. CONCLUSIONS: The clinical value of acoustic jitter, shimmer, and HNR may be limited if speaking voice SPL and professional voice use level effects are not controlled for. Future studies are warranted to investigate whether perturbation measures are useful clinical outcome metrics when controlling for these effects. Study Design: Matched case-control study Methods: 58 adult female voice patients, matched according to approximate age and occupation with 58 vocally healthy women, were assessed. Diagnoses included vocal fold nodules (n:39, 67.2%), polyps (n:5, 8.6%), and muscle tension dysphonia (MTD; n:14, 24.1%). All participants sustained the vowel /a/ at soft, comfortable, and loud phonation levels. Acoustic voice SPL, jitter, shimmer, and HNR were computed using Praat. The effects of loudness condition, voice SPL, pathology, differential diagnosis, age, and professional voice use level on acoustic perturbation measures were assessed using linear mixed models and Wilcoxon signed-rank tests.Results: In both patient and normative control groups, increasing voice SPL correlated significantly (p<0.001) with decreased jitter and shimmer, and increased HNR. Voice pathology and differential diagnosis were not linked to systematically higher jitter and shimmer. HNR levels, however, were statistically higher in the patient versus control group at comfortable phonation levels. Professional voice use level had a significant effect (p<0.05) on jitter, shimmer, and HNR.Conclusions: The clinical value of ac...

The acoustic voice quality index version 02.02 in the Finnish-speaking population

“…Earlier results have shown that acoustic measures of hoarseness such as jitter and shimmer values, SN ratio and cepstral measures, react to voice loudness: better values are obtained when speaking more loudly and vice versa (e.g. [42][43][44]. To summarize, the results revealed that there is an overlap in the AVQI scores between different levels of perceived abnormality of voice.…”

Effect of vowel context in cepstral and entropy analysis of pathological voices

“…While the performance of CPPS was better using excerpted vowels, SampEn exhibited greater AUC and accuracy in sustained vowels. It has been shown in earlier studies that perturbation and other voice quality measures such as jitter, shimmer, and harmonics-to-noise ratio (HNR) show improved values (smaller for jitter/shimmer, larger for HNR) with higher vocal intensity [39,40]. For the analyzed dataset, the sustained vowels of both pathological subjects and controls had on average a higher intensity compared to the excerpted vowels by 2.9 dB (std 5 dB).…”

Vocal characteristics of 5-year-old children: proposed normative values based on a French-speaking population†

“…Perturbation indices are influenced by voice intensity: an increase in voice intensity implies increased vocal cord tension, which makes it possible to stabilize the vocal cords and reduce the variability from one vibratory cycle to another. Thus, the higher the intensity of the voice, the lower jitter and shimmer will be [47].…”

“…NHR is also influenced by voice intensity: the louder the subject speaks, the less noise there is in the voice and thus the lower NHR will be [47].…”