Vocal quality assessment: methodological approach for a perceptive data analysis

Abstract

Purpose: to present a methodological approach for interpreting perceptual judgments of vocal quality by a group of evaluators who used the script Vocal Profile Analysis Scheme. Methods: cross-sectional study based on 90 speech samples from 25 female teachers with voice disorders and/or laryngeal changes. Prior to the perceptual judgment, we performed three perceptual tasks to select samples which were then presented to five evaluators using the Experiment script MFC 3.2 (software PRAAT). Next, we applied a sequence of tests based on successive approaches to inter-and intra-evaluator behavior. Data were treated by statistical analysis (Cochran and Selenor tests).Results: with respect to the analysis of the evaluators' performance, it was possible to define those that presented the best results, in terms of reliability and proximity of analyses, compared to the most experienced evaluator, excluding one. The results of the cluster analysis also allowed designing a voice quality profile of the group of speakers studied. Conclusions: the proposal of a methodological approach allowed defining evaluators whose judgments were based on phonetic knowledge, and drawing a vocal quality profile of the group of samples analyzed.

Acurácia das medidas acústicas tradicionais e formânticas na avaliação da qualidade vocal

“…It may be inferred from these findings that compared to individuals without voice quality deviation, patients with a mild to moderate degree of deviation may implement supraglottic adjustments to compensate for dysfunctional glottic conditions with the presence of increased silent airflow. These findings are consistent with other studies (8)(9)(10)(13)(14)(15) showing that dysphonic patients tend to make adjustments in the vocal tract to compensate for their voice problem.…”

“…The increase in F1 values is related to the greater lowering of the oromandibular complex and to oropharyngeal narrowing (6)(7)(8)10,11) . These cited supraglottic adjustments may occur as a compensation for dysfunctional glottic conditions, as a greater degree of jaw opening and pharyngeal narrowing may cause a decrease in auditorily perceived breathiness (27) and increased voice intensity (8)(9)(10)17) . An increase in F1 is also associated with the phonatory effort present in dysphonic patients with muscular tension (14) .…”

“…The F 0 measure was present in most of the combinations when discriminating predominant voice quality, which attests to the results found in previous studies (8,13,18,29,30) in which the fundamental frequency appeared to be an interesting measure when discriminating voice quality. This is probably because it is related, in physiological terms, to the neuromuscular condition and vocal fold mucosa vibration regularity, and in acoustic and perceptual terms, it is directly related to the sound signal periodicity (6,9,11,30) .…”

“…The vocal tract has a three-dimensional configuration and the sound that is produced in the glottis is modified by the positioning of structures such as the larynx, soft palate, tongue, lips and jaw. The frequencies of the glottal signal that are reinforced by the supraglottic vocal tract are called formants, and their analysis provides information about adjustments being made in the supraglottic vocal tract (6)(7)(8)(9)(10) .…”

“…Some studies (8)(9)(10)(13)(14)(15) have observed that patients with a voice disorder make adjustments not just in the glottis but also in the supraglottis. These patients have lower formant values (F1, F2, F3) than individuals without a voice disorder (10,13,15) .…”