Usefulness of Vocal Fatigue Index for Hypertension of Extrinsic Laryngeal Muscles

Background and Objectives This study compares Vocal Fatigue Index (VFI) scores according to the presence or absence of external laryngeal tension in hyperfunctional voice disorder. And through this, it is to confirm the usefulness of VFI to hypertension of extrinsic laryngeal muscles.Materials and Method The subjects were 61 female diagnosed with hyperfunctional voice disorder (hypertension group 41, non-hypertension group 20). The author palpated extrinsic laryngeal muscles for evaluation of hypertension and classified them as the presence or absence. The voice measurements were jitter, shimmer, Korean-Voice Handicap Index-10 (K-VHI-10), and Korean-Vocal Fatigue Index (K-VFI). The voice compared were according to the diagnosis and presence of hypertension only for patients with hyperfunctional voice disorder.Results As a result of comparing the voice measurement according to the presence or absence of hypertension, there was no significant difference in the acoustic variables, K-VHI-10 and K-VFI-Total, K-VFI-Fatigue. Whereas, K-VFI-Physical (p=0.006) and K-VFI-Rest (p=0.022) were significantly higher in the hypertension group.Conclusion These results indicate that the hypertension group has more physical discomfort and less voice recovery than the group without hypertension. It means that K-VFI can measure the physical discomfort and limitations of voice recovery due to hypertension of the external laryngeal muscle. The VFI can be used as one of the methods to evaluate the hypertension of the external laryngeal muscle in Hyperfunctional voice disorder.

The Effects of a Vocal Loading Task on the Acoustic and Electromyographic Measurements of Vocal Fatigue

The purpose of this study was to determine the effect of a vocal loading task on submandibular muscular activity and acoustic measures of vocal function. Surface electromyography (sEMG) directly assessed muscle activation related to extrinsic laryngeal muscles, and these findings were compared to the acoustic measurements of cepstral peak prominence, low to high spectral ratio, semitone range, and amplitude reflecting the function of intrinsic laryngeal muscles. These measurements were taken from 14 healthy, young adults of the Texas Christian University student population before and after reading Harry Potter and the Sorcerer’s Stone for 30 minutes at a volume of at least 75 decibels (dB). Results indicated consistent trends in which acoustic measurement showed more periodic vocal fold movement and reduced vocal range, and sEMG measurement showed reduced muscle activation. An elevated acoustic amplitude suggested that increasing vocal intensity could be a compensatory strategy for individuals with vocal fatigue, but further study is required to test this theory in a larger sample size.

Laryngeal Aerodynamics in Children with Hearing Impairment versus Age and Height Matched Normal Hearing Peers

Lack of proper auditory feedback in hearing-impaired subjects results in functional voice disorder. It is directly related to discoordination of intrinsic and extrinsic laryngeal muscles and disturbed contraction and relaxation of antagonistic muscles. A total of twenty children in the age range of 5–10 years were considered for the study. They were divided into two groups: normal hearing children and hearing aid user children. Results showed a significant difference in the vital capacity, maximum sustained phonation, and fast adduction abduction rate having equal variance for normal and hearing aid user children, respectively, but no significant difference was found in the peak flow value with being statistically significant. A reduced vital capacity in hearing aid user children suggests a limited use of the lung volume for speech production. It may be inferred from the study that the hearing aid user children have poor vocal proficiency which is reflected in their voice. The use of voicing component in hearing impaired subjects is seen due to improper auditory feedback. It was found that there was a significant difference in the vital capacity, maximum sustained phonation (MSP), and fast adduction abduction rate and no significant difference in the peak flow.

Comparison of Muscle Activation Patterns in Adductor and Abductor Spasmodic Dysphonia

Patients with adductor and abductor spasmodic dysphonia were compared with normal controls on speech items particularly difficult for the two patient groups. Intrinsic and extrinsic laryngeal muscles were measured during adduction for voicing and for a glottal stop, and during abduction after a vowel and after a glottal stop. Muscle activity was measured while the patients attempted the speech items, with considerable difficulty, but not during periods of complete voice loss. Muscle activity at rest, activity increases for speech, and percent changes for adduction and abduction did not differ from normal in either patient group. The results demonstrated normal muscle activation levels and changes for speech in the patients, and suggested that symptoms occur when spasmodic bursts intrude on an otherwise normal pattern.

An Evaluation of Laryngeal Muscle Activation in Patients with Voice Tremor

Eight patients with voice tremor were studied to characterize laryngeal muscle involvement. Electromyographic (EMG) recordings were made from intrinsic laryngeal muscles, simultaneously with some extrinsic laryngeal muscles, respiratory movement, and voice recordings during respiration, whisper, and phonation. Spectral measures were used to determine the tremor frequency and the prominence of spectral peaks in the EMG, respiratory and acoustic signals, while correlation coefficients were computed between pairs of tremulous EMG signals to measure the synchrony of tremor between muscles. The intrinsic laryngeal muscles were tremulous during respiration and speech, with the thyroarytenoid most often involved. Tremor was also detected in some of the extrinsic muscle recordings and the percentage of muscles with tremor was higher during phonation than during whisper or respiration. Time delays were found between tremor oscillations in laryngeal muscles. Because the thyroarytenoid was affected in all the patients studied, botulinum toxin injections may be beneficial in treatment of this voice disorder.

Multichannel Electromyographic Observations in Spasmodic Dysphonia Patients and Normal Control Subjects

Spasmodic dysphonia is primarily a disorder of vocalization. Increasing evidence, however, suggests that individuals with this disorder comprise a heterogeneous population characterized by abnormal motor control throughout the vocal tract. Multichannel simultaneous electromyography was performed on 11 spasmodic dysphonia patients and 10 normal awake subjects to investigate both the distribution of neuromotor abnormality within the vocal tract (eg, intrinsic and extrinsic laryngeal muscles, tongue, and palate) and the contribution of activation of higher central nervous system centers to observed abnormality. Experimental tasks ranged from vegetative (quiet breathing) to simple linguistic (short sentences). Digitized electromyographic signals were analyzed to compute the amplitude envelope and extract a set of parameters that represent amplitude characteristics. Electrode insertions were cross-validated by quantitative analysis of patterns of activation across selected reference tasks and by traditional qualitative methods. Between-group differences were found for measures of normalized median and peak token amplitudes. These differences are both task- and measure-dependent. Results highlight the complex and interactive effects of muscle, task, and quantitative measures on between-group differences.