Clinical applications of electroglottography

Electroglottography (EGG) is a method to monitor the vibrations of the vocal folds by measuring the varying impedance to a weak alternating current through the tissues of the neck. The paper is an attempt to give a state-of-the-art report of how electroglottography is used in the clinic. It is based on a search of the pertinent literature was well as on an inquiry to 17 well known specialists in the field. The EGG techniques are described and limitations to the method are pointed out. Attempts to document voice quality by EGG are recognized and computerized methods to obtain information about vibratory perturbations and/or the vibratory frequency of the vocal folds are described. The author's personal conclusion is that the EGG signal is especially well suited for measurements of the glottal vibratory period. In the clinic such measurements are useful for periodicity analysis, as a basis for recording intonation contours, and to establish the characteristics of the voice fundamental frequency.     

Comparison of the Produced and Perceived Voice Range Profiles in Untrained and Trained Classical Singers

Frequency and intensity ranges (in true decibel sound pressure level, 20 microPa at 1 m) of voice production in trained and untrained vocalists were compared with the perceived dynamic range (phons) and units of loudness (sones) of the ear. Results were reported in terms of standard voice range profiles (VRPs), perceived VRPs (as predicted by accepted measures of auditory sensitivities), and a new metric labeled as an overall perceptual level construct. Trained classical singers made use of the most sensitive part of the hearing range (around 3-4 kHz) through the use of the singer's formant. When mapped onto the contours of equal loudness (depicting nonuniform spectral and dynamic sensitivities of the auditory system), the formant is perceived at an even higher sound level, as measured in phons, than a flat or A-weighted spectrum would indicate. The contributions of effects like the singer's formant and the sensitivities of the auditory system helped the trained singers produce 20% to 40% more units of loudness, as measured in sones, than the untrained singers. Trained male vocalists had a maximum overall perceptual level construct that was 40% higher than the untrained male vocalists. Although the A-weighted spectrum (commonly used in VRP measurement) is a reasonable first-order approximation of auditory sensitivities, it misrepresents the most salient part of the sensitivities (where the singer's formant is found) by nearly 10 dB.     

Acoustic analysis of voice in multiple sclerosis patients

The objective is to investigate the presence of dysphonic symptoms in multiple sclerosis (MS) patients and to compare quantitative acoustic parameters in multiple sclerosis patients and normal individuals. The method of study was an 8-month controlled cross-sectional that was carried out with 106 individuals (30 MS, 76 controls). Both groups included males and females from 20 to 55 years. Exclusion criteria were prior vocal disorder, laryngeal microsurgery, recent endotracheal intubation, tumors, laryngeal, lung or mediastinal metastases, respiratory disease, and other associated neurological diagnoses. For dysphonic symptoms (qualitative variables), associations were assessed using Mantel-Haenszel's chi2 test, with Yates correction or the Fisher exact test when necessary. Statistical significance was set at p< or =0.05. Dysphonia was observed in 70% of MS individuals versus 33% of controls (p=0.01). Association was found between MS and dysphonia (OR: 2.2, CI 95%: 1.13-4.25). Fundamental frequency was higher among MS patients (p=0.01). Fundamental frequency deviation was significantly higher in MS women (but not men) than controls (p=0.00). Jitter was higher in MS men than in all other groups (p=0.00). Results suggest that evaluation and treatment of MS patients should be revised, evaluating voice alterations in relation to other signs. MS seems to intensify gender effect on fundamental frequency deviation, noise, and jitter, with MS women presenting fewer voice variations than men.     

Comparisons of Voice Onset Time for Trained Male Singers and Male Nonsingers During Speaking and Singing

This study was designed to examine the temporal acoustic differences between male trained singers and nonsingers during speaking and singing across voiced and voiceless English stop consonants. Recordings were made of 5 trained singers and 5 nonsingers, and acoustically analyzed for voice onset time (VOT). A mixed analysis of variance showed that the male trained singers had significantly longer mean VOT than did the nonsingers during voiceless stop production. Sung productions of voiceless stops had significantly longer mean VOTs than did the spoken productions. No significant differences were observed for the voiced stops, nor were any interactions observed. These results indicated that vocal training and phonatory task have a significant influence on VOT.     

The singing/acting voice in the mature adult

With years of training and performance, the mature vocal performer experiences less vocal changes with aging than does his/her age peer who is not a performer. We have considered, some physical problems that may adversely influence the voice of the older performer. With some awareness and effective management of these possible problems, the negative effects on the older performer's voice can be minimized.     

Airway Considerations for Professional Singers—A Survey of Expert Opinion

The objective of this study was to survey physician experts in voice disorders/treatment to establish consensus guidelines for translaryngeal intubation (TLI) and tracheotomy when treating professional singers or other voice professionals. A written survey was sent to all physician members of the Voice Foundation seeking opinions/recommendations about route of TLI, duration of TLI before tracheotomy, size of endotracheal and tracheotomy tubes, and special interventions during patient care as these might differ between professional singers and nonsingers. Fifty-five percent of the physicians responded, of whom 73% classified their experience in voice care as “extensive.” A strong consensus (76%) favored a smaller endotracheal tube for singers (6–7 mm I.D. for males and 6.0 mm I.D. for females) via the oral (46%) versus nasal (36%) route. Intubation/extubation by the most expert/experienced personnel was emphasized so as to minimize direct trauma to the larynx. While intubated, strong recommendations were made to suppress gastric acid production and to minimize motion of the endotracheal tube, including patient sedation. Preferences for an early tracheotomy (6 days) versus their usual time (10 days) were approximately equal (44% vs. 50%, respectively) and most respondents (69%) recommended the same size tracheotomy tube (8.0 mm I.D. for males and 6.0 mm I.D. for females) for singers and nonsingers. Post extubation/decannulation care emphasized voice rest, retraining, continued gastric acid suppression, and the possibility of direct laryngoscopy to assess post-TLI or tracheotomy injuries.     

Assessing outcomes for dysphonic patients

This study was designed to evaluate a disease-specific outcome measure for patients with selected voice disorders and to relate this instrument to a standardized quality of life measurement. In addition, the study attempts to document the degree of handicap for dysphonia patients globally, between different vocal pathologies, and in comparison to other chronic diseases. In this prospective, observational study, 260 adult patients evaluated for alterations of voice completed a general quality of life measure (the Medical Outcomes Trust Short Form 36-Item[SF-36]) and a voice-specific instrument (Voice Handicap Index [VHI]) pretreatment.

The highest correlation was between the social functioning score of the SF-36and the total score of the VHI and the physical, emotional, and functional subscales (p < 0.001) of the VHI. Significant correlation was also obtained for the SF-36 domains mental health (p < 0.01), general health (p < 0.01), and role functioning emotional (p < 0.017) with the three VHI domains and the total VHI score. Patients had significantly lower scores than the general U.S. population in five of the eight domains of SF-36. Patients with vocal fold paralysis had the highest level of pretreatment disability as measured on both the VHI and SF-36 among voice patients. The patients with dysphonia had a lower level of physical functioning than the patients with chronic sinusitis (p < 0.01), reflecting a greater handicap. In addition, the dysphonia group had lower levels of social functioning than the angina (p < 0.01) and sciatica (p < 0.01) groups and a lower score for mental health than the angina group (p < 0.01).

The SF-36 correlates with the VHI in the domains of social functioning,mental health, and role functioning emotional. The baseline handicap for voice disorders represents a significant disability even in comparison to conditions such as angina pectoris, sciatica, and chronic sinusitis.     

The Relationship Between VHI Scores and Specific Acoustic Measures of Mildly Disordered Voice Production

This study was designed to examine the relationship between the Voice Handicap Index (VHI) and acoustic measures of voice samples common in clinical practice. Fifty participants, 38 women and 12 men, ranging in age from 19 to 80 years, with a mean age of 49 years, served as participants. Of these 50 participants, 17 participants could be included in the acoustic analysis of voice based on measures of error calculated with the TF32 software. All participants completed the VHI and provided voice samples including three trials of the sustained vowel /A/ at a comfortable loudness level as well as a connected speech sample consisting of the Zoo Passage. Acoustic measures were made with TF32 and Cool Edit software and included fundamental frequency, jitter %, shimmer %, signal-to-noise ratio, mean root-mean-square intensity, fundamental frequency standard deviation, aphonic periods, and breath groups. Results indicate that these measures were not predictive of overall VHI score, and no cohesive or predictable pattern was identified when comparing individual measures with overall VHI or with each subscale item. Likely contributions to this lack of correlation and subsequent clinical implications are discussed, as well as the direction for further research.     

Neurovegetative symptoms and complaints before and after voice therapy for nonorganic habitual dysphonia

In a previous study, female patients in all age categories with a nonorganic dysphonia were found to report significantly more autonomic symptoms and complaints than healthy controls. This could not be confirmed for the male subgroup. The present study is to corroborate and nuance this observation by investigating larger groups, and to determine if, after voice therapy, the number of autonomic symptoms and complaints-particularly those ones that have no obvious relation to voice function-decreases. It is a prospective study with a matched control group; 184 patients with nonorganic dysphonia and 126 normal controls answered a questionnaire of 46 questions with 3 subsets and a consistency control. One hundred and one patients received functional voice therapy and completed the questionnaire before and after treatment. A matched control group of 42 normal subjects also filled in the questionnaire two times, with an interval of about 6 months. Neurovegetative symptoms and complaints-voice related and not related-are reported in highly significant excess by patients (especially but not exclusively females) with habitual nonorganic voice disorder. After therapy, there is a highly significant reduction in the number of autonomic symptoms and complaints (related or not related to voice), to such an extent that patients report on average no more general neurovegetative symptoms and complaints than healthy controls (even less). The number of neurovegetative symptoms and complaints connected with voice function is also strongly reduced in patients after therapy, but remains in significant excess when compared with controls.     

Expanding perspectives in care of the speaking voice

The effective voice clinician has always had to borrow from various disciplines: voice science, otolaryngology, psychology, and speech-language pathology. Such eclecticism requires, however, that the clinician integrate the perspectives of these various disciplines into some kind of theoretical clinical bias. One bias might be that with greater use of instrumentation in voice therapy, the voice clinician must not substitute data collection for attending to the feelings of the patient. By using the clinical input from various disciplines, for example, voice clinicians might develop a useful clinical perspective that vocal hyperfunction is one of the primary causes of many voice disorders. Consequently, from such a clinical view might come a treatment perspective that can clearly define the problem (too much effort while speaking) and offer a rationale for voice remediation.