Glottographic signal perturbation in biomechanically different types of dysphonia

Multiparameter Voice Assessment in Dysphonics: Correlation Between Objective and Perceptual Parameters

BACKGROUND

Perceptual assessment and objective measures of voice provide a quantifiable tool for determining the degree of glottal closure, thus helping to distinguish dysphonic voices from normal voices. The correlation between the perceptual and objective parameters of voice in dysphonic can enable the voice pathologist to be more effective in differentiating the normal voices from dysphonic voices. However, only a few studies have investigated the correlation between these measures.

OBJECTIVE

To document the differences in the perceptual and objective parameters of voice in participants with dysphonia and normal controls and to investigate the correlation between the perceptual and objective parameters of voice among participants with dysphonia.

STUDY DESIGN

This investigation deployed standard group comparison and a retrospective study.

METHODS

Two groups of participants were included in the study. Participants in group 1 were diagnosed as having a voice disorder secondary to organic pathologies and group 2 participants had a clinically normal voice. Phonation samples of all the participants were collected and perceptual analysis was carried out using the GRBAS rating scale. As part of the objective measures, acoustic and cepstral measures were extracted from the phonation samples.

RESULTS

The analysis of the results revealed significant differences in perceptual ratings between the normal (control) and dysphonic groups. The mean values of all the objective measures of voice presented significant differences between participants of both groups. The perceptual ratings of grade, breathiness, and roughness showed better correlations with the cepstral measures than with the time-based acoustic measures.

CONCLUSIONS

Further foraging research on the correlation between perceptual and objective measures of voice in various degrees of dysphonia will improve reliability while discriminating and quantifying hoarse, harsh and breathy voices from modal voices.

Does Cervical Muscular Contraction Affect the Measurement for Electroglottographic Perturbation Parameters?

OBJECTIVES

The purpose was to assess whether cervical muscular contraction during phonation influences the period and amplitude perturbation quotients (PPQ and APQ, respectively) of electroglottographic (EGG) signals, and whether high-pass filtering can attenuate these effects.

STUDY DESIGN

Prospective.

METHODS

We included 19 nondysphonic speakers and 21 patients with muscle tension dysphonia. During the recording of acoustic and EGG signals, each participant was instructed to naturally phonate sustained vowels /i:/ and /a:/ (NP tasks), and additionally, each nondysphonic participant was asked to phonate the same vowels in a nondysphonic voice quality while contracting the cervical muscles (muscular contracted phonation [MCP] tasks). To confirm the contraction, surface and needle electromyography (EMG) was performed. The EGG signals were high-pass filtered at different cutoff frequencies from 0 to 90 Hz and were subsequently analyzed for the PPQ and APQ.

RESULTS

Compared with the NP tasks, the MCP tasks enhanced the cervical EMG activities ranging from 0 to more than 1000 Hz, but conferred only low-frequency noise to the EGG signals under 50 Hz and increased the values for EGG-APQ, but not EGG-PPQ. These EGG-APQ values exhibited gradual decreases after high-pass filtering with an increase in the cutoff frequency ranging from 0 to 50 Hz in both groups, followed by plateaus during the MCP tasks in the nondysphonic group.

CONCLUSIONS

The present results demonstrate that cervical muscular contraction seriously affects the EGG-APQ values for unfiltered EGG signals independent of the EMG activities and that appropriate high-pass filtering over 50 Hz can attenuate these effects.

Objective acoustic analysis of pathological voices from patients with vocal nodules and polyps

OBJECTIVE

We aim to examine the abilities of objective acoustic analysis methods (nonlinear dynamic and traditional perturbation measures) to describe voices from individuals with vocal nodules and polyps.

SUBJECTS AND METHODS

Sustained vowel recordings from normal subjects, patients with vocal nodules, and patients with vocal polyps were analyzed. Perturbation measures of jitter and shimmer were obtained with the Multi-Dimensional Voice Program (MDVP) and CSpeech. Signal-to-noise ratio was calculated using CSpeech. Nonlinear dynamic measures of phase space reconstruction and correlation dimension were also applied to analyze the voices.

RESULTS

A significant difference between normal and polyp groups was found in jitter and shimmer obtained from MDVP, as well as in jitter and signal-to-noise ratio from CSpeech. However, no parameters significantly differentiated between normal and nodule groups. Shimmer from CSpeech did not reveal any significant differences among any of the groups. Correlation dimension values for the nodule and polyp groups were significantly higher than the normal group.

CONCLUSION

Nonlinear dynamic analysis has great potential value for the characterization of voice from patients with vocal nodules and polyps. The combination of traditional perturbation and nonlinear dynamic measures may improve our ability to provide objective clinical analysis of voices with vocal mass lesions.

Electroglottographic and acoustic changes following type I thyroplasty or autologous fat injection

This study identified the electroglottographic (EGG) and acoustic measures that were most predictive of change in the glottic gap size of patients undergoing type I thyroplasty or autologous fat injection. Simultaneous EGG and acoustic recordings were made before and after autologous fat injection in 23 patients and type I thyroplasty in 45 patients. Relative measures of glottic gap size were obtained before and after operation from videostroboscopic images. Regression and correlation analysis was used to determine the strength of associations between the EGG or acoustic measures and glottic gap changes. A significant regression equation for both patient groups was constructed. The strongest predictors of glottic gap size change were changes in the EGG open quotient, signal-to-noise ratio, and mean fundamental frequency. Glottography provided a clinically useful means of evaluating glottic gap changes in patients undergoing vocal fold medialization procedures. Preoperative-postoperative differences in signal-to-noise ratio and mean fundamental frequency also were correlated to glottic gap size changes, but to a lesser degree.

Effect of tape recording on perturbation measures

Tape recorders have been shown to affect measures of voice perturbation. Few studies, however, have been conducted to quantitatively justify the use or exclusion of certain types of recorders in voice perturbation studies. This study used sinusoidal and triangular waves and synthesized vowels to compare perturbation measures extracted from directly digitized signals with those recorded and played back through various tape recorders, including 3 models of digital audio tape recorders, 2 models of analog audio cassette tape recorders, and 2 models of video tape recorders. Signal contamination for frequency perturbation values was found to be consistently minimal with digital recorders (percent jitter = 0.01%-0.02%), mildly increased with video recorders (0.05%-0.10%), moderately increased with a high-quality analog audio cassette tape recorder (0.15%), and most prominent with a low-quality analog audio cassette tape recorder (0.24%). Recorder effect on amplitude perturbation measures was lowest in digital recorders (percent shimmer = 0.09%-0.20%), mildly to moderately increased in video recorders and a high-quality analog audio cassette tape recorder (0.25%-0.45%), and most prominent in a low-quality analog audio cassette tape recorder (0.98%). The effect of cassette tape material, length of spooled tape, and duration of analysis were also tested and are discussed.