Studying vocal fold vibrations in Parkinson's disease with a nonlinear model

A nonlinear model is applied to study pathologic vocal vibratory characteristics and voice treatments of Parkinson's disease. We find that a number of pathologic vocal characteristics commonly observed in Parkinson's disease, including reduced vibratory intensity, incomplete vocal closure, increased phonation threshold pressure, glottal tremor, subharmonics, and chaotic vocal fold vibrations, can be studied with this nonlinear model. We also find that two kinds of clinical voice treatments for Parkinson's disease, including respiratory effort treatment and Lee Silverman voice treatment can be studied with this computer model. Results suggest that respiratory effort treatment, in which subglottal pressure is increased, might aid in enhancing vibratory intensity, improving glottal closure, and avoiding vibratory irregularity. However, the Lee Silverman voice treatment, in which both subglottal pressure and vocal fold adduction are increased, might be better than respiratory effort treatment. Increasing vocal fold thickness would be further helpful to improve these pathologic characteristics. The model studies show consistencies with clinical observations. Computer models may be of value in understanding the dynamic mechanism of disordered voices and studying voice treatment effects in Parkinson's disease.     

Autologous fat implantation for vocal fold scar: A preliminary report

New insights into the anatomy and physiology of phonation, along with technological advances in voice assessment and quantification, have led to dramatic improvements in medical voice care. Techniques to prevent vocal fold scar have been among the most important, especially scarring and hoarseness associated with voice surgery. Nevertheless, dysphonia due to vocal fold scar is still encountered all too frequently. Although it is not generally possible to restore such injured voices to normal, patients with scar-induced dysphonia can usually be helped. Voice improvement is optimized through a team approach. Treatment may include sophisticated voice therapy and vocal fold surgery. Although experience with collagen injection has been encouraging in selected cases (particularly in those involving limited areas of vocal fold scar), there is no consistently successful surgical technique. Attempts to treat massive vocal fold scar, such as may be seen following vocal fold stripping, have been particularly unsuccessful. This paper reports preliminary experience with the implantation of autologous fat into the vibratory margin of the vocal fold of patients with severe, extensive scarring. Using this technique, it appears possible to recreate a mucosal wave and improve voice quality. Additional research is needed.     

Laryngostroboscopic Evaluation After Supracricoid Partial Laryngectomy

BACKGROUND: Supracricoid partial laryngectomy (SCPL) results in laryngeal preservation in more than 95% of patients with T2 glottic carcinoma. Postsurgical glottic function is characterized by an absence of vocal cords, and phonation quality is a key post-SCPL quality-of-life factor. OBJECTIVE: This investigation was designed to enhance post-SCPL vocal function, study anatomic function of the post-SCPL larynx, and correlate anatomic findings with perceptual and instrumented measurements of voice. METHOD: Twenty-five patients were included. All had undergone SCPL with cricoepiglottopexy for T2 glottic carcinoma. All patients were evaluated by laryngostroboscopic examination, voice sample recording, and instrumented voice analysis with the aim of gaining further insight into postoperative larynx function. Laryngostroboscopic parameters such as laryngeal occlusion, epiglottic length, arytenoid movement, and vibratory area were assessed. The perceptual evaluation was based on the GRBAS scale. Acoustic and aerodynamic parameters were recorded, including fundamental frequency (F0), intensity, jitter, shimmer, signal-to-noise ratio (SNR), oral airflow (OAF), maximum phonation time (MPT), and estimated subglottic pressure (ESGP). Nonparametric tests were used to compare laryngostroboscopic parameters with instrumented measurements and perceptual evaluations of voice quality. RESULTS: Correlations were established among occlusion, epiglottic length, and general grade of dysphonia. Oral air flow (P = 0.006) was found to be correlated with occlusion. Voice roughness was correlated with the presence of a clearly identifiable vibratory area (P = 0.003), whereas these vibratory areas were correlated with shimmer (P = 0.041), OAF (P = 0.001), and SNR (P = 0.001). The number of preserved arytenoids was not identified as a voice quality factor (P = 0.423). CONCLUSION: This study highlighted correlations between the laryngostroboscopic examination results and the perceptive and instrumented measurements of voice. Glottis occlusion and epiglottis length were found to be key factors for postoperative voice quality. These results should help to advance technical development on surgical techniques to enhance voice results.     

Sex hormones and the female voice

In the following, the authors examine the relationship between hormonal climate and the female voice through discussion of hormonal biochemistry and physiology and informal reporting on a study of 197 women with either premenstrual or menopausal voice syndrome. These facts are placed in a larger historical and cultural context, which is inextricably bound to the understanding of the female voice. The female voice evolves from childhood to menopause, under the varied influences of estrogens, progesterone, and testosterone. These hormones are the dominant factor in determining voice changes throughout life. For example, a woman's voice always develops masculine characteristics after an injection of testosterone. Such a change is irreversible. Conversely, male castrati had feminine voices because they lacked the physiologic changes associated with testosterone. The vocal instrument is comprised of the vibratory body, the respiratory power source and the oropharyngeal resonating chambers. Voice is characterized by its intensity, frequency, and harmonics. The harmonics are hormonally dependent. This is illustrated by the changes that occur during male and female puberty: In the female, the impact of estrogens at puberty, in concert with progesterone, produces the characteristics of the female voice, with a fundamental frequency one third lower than that of a child. In the male, androgens released at puberty are responsible for the male vocal frequency, an octave lower than that of a child. Premenstrual vocal syndrome is characterized by vocal fatigue, decreased range, a loss of power and loss of certain harmonics. The syndrome usually starts some 4-5 days before menstruation in some 33% of women. Vocal professionals are particularly affected. Dynamic vocal exploration by televideoendoscopy shows congestion, microvarices, edema of the posterior third of the vocal folds and a loss of its vibratory amplitude. The authors studied 97 premenstrual women who were prescribed a treatment of multivitamins, venous tone stimulants (phlebotonics), and anti-edematous drugs. We obtained symptomatic improvement in 84 patients. The menopausal vocal syndrome is characterized by lowered vocal intensity, vocal fatigue, a decreased range with loss of the high tones and a loss of vocal quality. In a study of 100 menopausal women, 17 presented with a menopausal vocal syndrome. To rehabilitate their voices, and thus their professional lives, patients were prescribed hormone replacement therapy and multi-vitamins. All 97 women showed signs of vocal muscle atrophy, reduction in the thickness of the mucosa and reduced mobility in the cricoarytenoid joint. Multi-factorial therapy (hormone replacement therapy and multi-vitamins) has to be individually adjusted to each case depending on body type, vocal needs, and other factors.     

Voice research: So What? A clearer view of voice production, 25 years of progress; the speaking voice

The past 25 years has yielded an impressive growth in our knowledge of vocal function. Interdisciplinary research cooperation in areas of laryngeal histology, vocal aerodynamics and acoustics, vocal fold vibratory characteristics, neurolaryngology, and phonatory models has led to a clearer view of voice production. This article offers a brief review of the progress that has been made in our understanding of the speaking voice and relates this knowledge to clinical practice. The importance of utilizing voice research to confirm traditional management techniques and to develop new physiologically based management approaches is also stressed.     

Investigating acoustic correlates of human vocal fold vibratory phase asymmetry through modeling and laryngeal high-speed videoendoscopy

Vocal fold vibratory asymmetry is often associated with inefficient sound production through its impact on source spectral tilt. This association is investigated in both a computational voice production model and a group of 47 human subjects. The model provides indirect control over the degree of left-right phase asymmetry within a nonlinear source-filter framework, and high-speed videoendoscopy provides in vivo measures of vocal fold vibratory asymmetry. Source spectral tilt measures are estimated from the inverse-filtered spectrum of the simulated and recorded radiated acoustic pressure. As expected, model simulations indicate that increasing left-right phase asymmetry induces steeper spectral tilt. Subject data, however, reveal that none of the vibratory asymmetry measures correlates with spectral tilt measures. Probing further into physiological correlates of spectral tilt that might be affected by asymmetry, the glottal area waveform is parameterized to obtain measures of the open phase (open/plateau quotient) and closing phase (speed/closing quotient). Subjects' left-right phase asymmetry exhibits low, but statistically significant, correlations with speed quotient (r=0.45) and closing quotient (r=-0.39). Results call for future studies into the effect of asymmetric vocal fold vibration on glottal airflow and the associated impact on voice source spectral properties and vocal efficiency.     

Voice problems in a small swedish town: A retrospective study of the prevalence and a follow-up

The prevalence of voice problems among patients consulting the primary health care unit of a small Swedish town during 1984 was investigated. A study of the records of 11,606 patients indicated that 102 of them consulted their doctor mainly because of voice problems. The period prevalence of voice problems in the population of 20,049 people was 0.5%. A follow-up examination 1 year later indicated that 44% of these patients still had voice problems. Among the patients with a voice disorder diagnosis made by means of indirect laryngoscopy in 1984, 72% still had a voice disorder diagnosis at the follow-up. It is pointed out that the doctor who is seeing a patient with voice problems should make a thorough examination including indirect laryngoscopy. It is also important to discuss the patient's smoking habits and professional vocal strain to prevent recurrence.     

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.     

Functional Analysis of Voice Using Simultaneous High-Speed Imaging and Acoustic Recordings

We present a comprehensive, functional analysis of clinical voice data derived from both high-speed digital imaging (HSDI) of the larynx and simultaneously acquired acoustic recordings. The goals of this study are to: (1) correlate dynamic characteristics of the vocal folds derived from direct laryngeal imaging with indirectly acquired acoustic measurements; (2) define the advantages of using a combined imaging/acoustic approach for the analysis of voice condition; and (3) identify new quantitative measures to evaluate the regularity of the vocal fold vibration and the complexity of the vocal output -- these measures will be key to successful diagnosis of vocal abnormalities. Image- and acoustic-based analyses are performed using an analytic phase plot approach previously introduced by our group (referred to as 'Nyquist' plot). Fast Fourier Transform (FFT) spectral analyses are performed on the same data for a comparison. Clinical HSDI and acoustic recordings from subjects having normal and specific voice pathologies, including muscular tension dysphonia (MTD) and recurrent respiratory papillomatosis (RRP) were analyzed using the Nyquist plot approach. The results of these analyses show that a combined imaging/acoustic analysis approach provides better characterization of the vibratory behavior of the vocal folds as it correlates with vocal output and pathology.     

Acoustic Interpretation of Resonant Voice

Resonant voice, often described in terms of vibratory sensations in the face, is investigated acoustically by calculating vocal tract inertance. It appears that the ease of production and vibrancy of resonant voice depends more on lowering phonation threshold pressure than on tissue or air resonance in or around the face. Phonation threshold pressure is lowered by increasing air column inertance in the laryngeal vestibule. The fact that the sensations are felt in the face is an indication of effective conversion of aerodynamic energy to acoustic energy, rather than sound resonation in the sinuses or the nasal airways.     

From Voice Clinic to Operating Room: Are We Out of Tune?

Introduction: To determine the consistency and accuracy of preoperative diagnosis in the voice clinic with intraoperative diagnosis and to suggest a standardized laryngeal examination protocol in the UK that is supported by evidence-based findings.Method: From January 2011-September 2014, 164 patients were referred to the Multidisciplinary Team voice clinic and diagnosed with laryngeal pathology that required phonosurgery. The visualization (videostrobolaryngoscopy) in clinic was performed using either rigid laryngoscope or a video-naso-laryngoscope. Intraoperatively, laryngeal visualization and surgical procedure was conducted using Storz Aida HD system, 10-mm rigid laryngoscope 0° or 5-mm rigid laryngoscope 0°/30° and a Zeiss S7 microscope.Results: Of the 164 patients seen in the multidisciplinary voice clinic, 86 clinic diagnoses were confirmed intraoperatively (52.4%), 15 patients had the diagnosis confirmed intraoperatively with additional lesion found (9.1%). The clinic diagnosis changed intraoperatively in 63 cases (38.4%). 61 (37.2%) patients seen in the voice clinic were diagnosed with cyst, in 39.3% the diagnosis was confirmed intraoperatively with 5 cases (8.2%) having an additional diagnosis. Twenty (12.2%) patients were diagnosed with polyps, with 80% confirmation intraoperatively; 3 patients (10%) had an additional diagnosis.Conclusion: Videolaryngostroboscopy imaging of the larynx provides an outpatient tool for accurately diagnosing more than 50% of laryngeal pathologies when interpreted by multidisciplinary voice clinicians. However direct laryngeal examination under general anesthesia remains the gold standard when obtaining accurate diagnoses of laryngeal pathology. Patients diagnosed with nonorganic voice disorders should be considered for direct laryngoscopy under general anesthetic should they fail to respond to conservative management.     

Treatment of laryngeal contact ulcers and granulomas: A 12-year retrospective analysis

Multiple etiological factors including gastroesophageal reflux, hyperfunctional voice use, and endotracheal intubation have been implicated in the development of posterior laryngeal ulcers and granulomas. The optimal approach to treatment of these lesions remains controversial. The mainstay of treatment at Vancouver General Hospital has been aggressive medical management of gastroesophageal reflux, with complimentary voice therapy offered to patients suspected of having significant hyperfunctional phonation. The authors reserve Botulinum toxin injection or surgical excision for patients who fail initial therapy. They conducted a retrospective analysis of their voice clinic records from 1985–1997 to examine the efficacy of this approach. They identified 76 patients with the diagnosis of contact ulcer or granuloma. Fifty-two patients had follow-up data available for review. Ninety-four percent of patients were treated nonsurgically: 35 patients were treated solely by dietary and medical therapy to control gastroesphageal reflux, 10 patients were treated by a combination of medical gastroesophageal reflux control and voice therapy, 3 patients had Botox injections, 2 patients had surgical excision of granuloma, 1 patient had a Kenalog injection, and 1 patient underwent laparoscopic fundoplication. Overall, 77% of patients had complete resolution, whereas 11% had partial resolution and another 11% had no significant improvement. The data supports control of gastroesophageal reflux as a central component in treatment of posterior laryngeal ulcers and granulomas.     

Problems and pitfalls of electroglottography

The popularity and usefulness of the electroglottograph (EGG) has increased remarkably since its introduction over a decade ago. It has been used to measure fundamental frequency of phonation, fundamental frequency perturbation, details of the vocal fold vibratory cycle, as well as to provide an indication of laryngeal vertical movement. It has also been used with a variety of speech and voice disorders. The EGG is not without its limitations and problems. Some of these are found in the electronic designs of specific instruments, whereas other problems are related to subject characteristics, the placement of the electrodes, electrode symmetry, and subject/instrument interaction. This article explores some of these concerns, primarily from the perspective of two individuals who have used the EGG extensively with children, men and women, voice patients, stutterers, and neurologically impaired persons. Some of the concerns to consider and pitfalls to avoid in the interpretation and measurement of EGG signal are discussed.     

Analysis of Vocal-fold Vibrations from High-Speed Laryngeal Images Using a Hilbert Transform-Based Methodology

This paper presents a Hilbert transform-based approach to analyze vocal fold vibrations in human subjects exhibiting normal and abnormal voice productions. This new approach is applied to the analysis of glottal area waveform (GAW) and is capable of providing useful information on the vocal fold vibration. The GAW is extracted from high-speed laryngeal images by delineating the glottal edge for each image frame. An analytic signal is generated through the Hilbert transform of the GAW, which yields a recognizable pattern of the vocal fold vibration in the analytic phase plane. The vibratory pattern is comprehensive and can be correlated with specific voice conditions. Quantitative measures of the glottal perturbation are introduced using the analytic amplitude and instantaneous frequency obtained from the analysis. Examples of clinical voice recordings are used to evaluate and test the effectiveness of this approach in providing qualitative representation and quantitative characteristics of vocal fold vibratory behavior. The results demonstrate the potential of using this new analytical tool incorporated with the high-speed laryngeal imaging modality for clinical voice assessment.     

Allergies and vocal fold edema: A preliminary report

This paper describes different tools to rule out the etiology of vocal fold edema. A complete voice assessment is used in our Voice Center. This includes patient history, acoustic analysis, laryngeal video-stroboscopy, otolaryngology consultation, allergy testing from our Allergy Clinic, and gastroenterology consultation as appropriate. Inhalant allergy can be a hidden, yet very common cause of chronic laryngitis. Respiratory allergies can also cause decreased pulmonary function; excessive secretions in either the lower airway, trachea, bronchi or in the upper airway of the pharynx; edema of the vocal folds themselves; and unusual resonance characteristics of the pharynx or nasal cavity due to congestion of the membrane in those areas. Voice patients with a history of seasonal hay fever, a history of allergic reactions around cats or dogs, or a strong family history of allergies should be allergy tested. Screening tests for allergies are available, which include a screening radioallergosorbent test or a screening panel of scratch or intradermal skin tests. Once specific allergens are identified, recommendations for therapy or other intervention can be made. Straining the voice, in combination with the above conditions, can increase the voice problem. The histories, allergy test results, and voice laboratory evaluations of several patients are described. Identifying these voice patients and treating their allergies are important in keeping these patients healthy and maintaining a clear, good voice quality. The multidisciplinary approach in voice disorders is indispensable in diagnosis and treatment of these disorders.     

Some physical characteristics of the male falsetto voice

Previous research indicated that, as groups, male (bass/baritone) and female (soprano) professional singers tend to exhibit differing vocal tract and voice source behaviours. The use of an objective measure of voice [xeroradiographic-electrolaryngographic analysis (XEL)] revealed differences between the two voice types, especially at the highest sample pitches (e, 330 Hz for bass/baritones, and e″, 1,320 Hz for sopranos). XEL analysis combines two known techniques, i.e., soft-tissue radiographic imaging (xeroradiography), and an analysis of voice-source vibratory patterning (electrolaryngography). Subsequent to this investigation, interest centered on the male professional falsetto voice over a two-octave range (E 165 Hz to e′ 660 Hz) using a sample (n=9) of professional countertenors. Results suggest that there are characteristic trends in the patterning of the male professional falsetto register, but there is also evidence of within-group variability. The subjects significantly increased the size of the pharyngeal tube area during phonation. ANOVA and Trend Analysis revealed ventricular space as the only measure to expand systematically and consistently as sung pitch increases.     

Voice disorders in patients with suspected laryngo-pharyngeal reflux disease

Many symptoms have been recognized in association with laryngo-pharyngealreflux disease (LPRD), but reports of perceptual voice disorders in this condition have been lacking to date. Forty-nine patients with suspected LPRD were studied for five specific perceptual voice characteristics, and these characteristics were compared to the same characteristics in individuals who had never seen an Otolaryngologist for a voice disorder or throat problem (controls). Sixteen of the suspected LPRD patients also underwent 24-hour pH probe studies. All patients with suspected LPRD had significantly increased abnormal perceptual voice characteristics (musculoskeletal tension, hard glottal attack, glottal fry, restricted tone placement, and hoarseness) compared to the controls. Statistical objective differences between the two groups was demonstrated by the presence of increased shimmer in patients with suspected LPRD compared to controls. The differential diagnosis between functional voice disorders and LPRD may be complex, and perceptual parameters may overlap. Interdisciplinary evaluation is advocated.     

Voice source characteristics in Mongolian "throat singing" studied with high-speed imaging technique, acoustic spectra, and inverse filtering.

Mongolian "throat singing" can be performed in different modes. In Mongolia, the bass-type is called Kargyraa. The voice source in bass-type throat singing was studied in one male singer. The subject alternated between modal voice and the throat singing mode. Vocal fold vibrations were observed with high-speed photography, using a computerized recording system. The spectral characteristics of the sound signal were analyzed. Kymographic image data were compared to the sound signal and flow inverse filtering data from the same singer were obtained on a separate occasion. It was found that the vocal folds vibrated at the same frequency throughout both modes of singing. During throat singing the ventricular folds vibrated with complete but short closures at half the frequency of the true vocal folds, covering every second vocal fold closure. Kymographic data confirmed the findings. The spectrum contained added subharmonics compared to modal voice. In the inverse filtered signal the amplitude of every second airflow pulse was considerably lowered. The ventricular folds appeared to modulate the sound by reducing the glottal flow of every other vocal fold vibratory cycle.     

Voice Therapy Outcome—A Randomized Clinical Trial Comparing Individual Voice Therapy,Therapy in Group,and Controls Without Therapy

ObjectiveA stumbling-block in voice therapy is how the patient will be able to apply the new voice technique in everyday life. Possibly this generalization process could be facilitated by giving voice therapy in group because of the natural forum for training voice-to-speech early in communication between the patients in a group setting. The aim of the study was to compare treatment results from individual voice therapy and voice therapy in group, at several time points and in comparison to patients with no voice therapy.MethodsA randomized treatment study was performed with 77 consecutive patients diagnosed with a functional voice disorder. Thirty-one patients were randomized to individual and group therapy, respectively, and 15 patients to no therapy. The assessments included standardized voice recording and registration of voice range profile (VRP), answering Voice handicap index (VHI) and visual analogue scales for self-hoarseness and self-vocal fatigue, and perceptual voice evaluation by speech-language pathologist. The assessments were performed before, direct after therapy, and three months later in all groups. The 2 therapy groups were also assessed 12 months after therapy.ResultsAll VHI scores as well as the self-ratings of hoarseness and vocal fatigue, and the perceptual evaluation of voice quality and maximum VRP improved significantly in both therapy groups 3 months after treatment and at 12 months follow-up. There were no significant changes in the control group, with the exception of decreased self-rated hoarseness and increased maximum VRP. Comparisons between treatment groups showed significant larger improvement after group therapy for VHI physical subscale at 12 months, as well as significant lower VHI total score at all measurement sessions and lower subscale scores at 12 months. There were no differences between treatment groups in self-hoarseness or self-vocal fatigue and no difference in perceptual voice quality or VRP. Comparison between controls and treatment groups showed significant larger change in treatment groups from baseline to three months in VHI total and to end of therapy in functional subscale. Treatment groups also showed significant lower scores than controls at each measurement session, for VHI total and physical subscale as well as lower degree of perceptual aberration of voice quality and vocal fatigue, at three months follow-up.ConclusionsThis study shows long-term improvement from behavioral voice therapy, particularly in a group setting. The results indicate the importance of early transfer-to-speech and late posttherapy test to capture whether the goal of voice therapy was fulfilled or not for the patients.