Correlation between vocal functions and glottal measurements in patients with unilateral vocal fold paralysis

Observations and analysis of glottal characteristics are critical in choosing the best modality for surgery in patients with unilateral vocal fold paralysis (UVP). This study suggests that multiple glottal characteristics influence the vocal product in patients with UVP. In addition to the horizontal position of the paralyzed vocal fold (deviation from the midline), the glottal area, degree of bowing of the paralyzed and contralateral vocal folds, maximum separation between vocal folds, compensatory glottal maneuvers, and the vertical glottic closure plane significantly influenced the quality of the voice. Clinicians should be aware of these observations to facilitate treatment planning and assessment of the results of surgical procedures used to improve voice quality in cases of UVP.     

Financing changes of schistosomiasis control programmes in China 1980-1995: a case study in Songzi county

The biomechanics of arytenoid adduction surgery are not well understood. An excised canine larynx model was used to study the effects of variable suture tension on glottal configuration and on vocal fold tension (at the midfold and the vocal process). Arytenoid adduction both medializes the vocal fold and closes a posterior glottal chink. Vocal fold tension at the midfold did not vary significantly with suture tension. As suture tension increased to approximately 100 g, vocal fold tension at the vocal process also increased. Beyond 100 g of suture tension, vocal fold tension at the vocal process did not increase. We conclude that the effects of suture tension on the resistance to lateral movement are different at the midfold compared to the vocal process. Procedures for surgical rehabilitation of vocal fold paralysis should address the biomechanical subunits of the larynx individually in order to achieve optimum results.     

Analysis of pathological vocal fold vibrations using high-speed digital imaging

There have been various methods devised to monitor vocal fold vibration. Stroboscopy provides clinically-celevant information concerning pathology of the vocal folds. However, slow motion observation is based on the regularity of the vibration, and this ignores the role of irregularity of the vocal fold vibration in pathological cases. In order to know more about the nature of the vocal fold vibratory pattern, it is essential to monitor the vibration on a cycle by cycle basis. We analysed vocal fold vibrations of 22 pathological larynges using a computer-assisted high-speed digital imaging technique. Observed items included symmetry, regularity, phase difference, glottal closure, amplitude, mucosal wave and periodicity difference. Vibratory patterns were classified by location of lesion, severity of disease, expiratory pressure and laryngeal modulation. Analyses of pathological vocal fold vibrations using high-speed digital imaging techniques are providing the theoretical support for voice therapy and elucidating the causes of hoarseness.     

Assessment of vocal function using simultaneous aerodynamic and calibrated videostroboscopic measures

Despite many attempts to model how vocal fold movements relate to the aerodynamic forces acting on them during phonation, there have been few simultaneous measurements of glottal area and transglottal air pressures and flows. A novel system is described that combines endoscopic measurement of glottal area with aerodynamic flow and pressure measures made during phonation. Results from bench top model tests and from one human subject are presented. For both tests, an aerodynamic model of airflow through a constriction was used to predict the area of the constriction (glottis), and these predictions were compared with endoscopic measurements. The results showed good correlation between predicted and observed areas; however, for small constrictions (<0.025 cm2), whether artificial or glottal, the errors in estimating areas with either optical or aerodynamic methods increase significantly. These results suggest that this measurement system has the potential to enhance the assessment of vocal function.     

Parameterization of the voice source by combining spectral decay and amplitude features of the glottal flow

A new method is presented for the parameterization of glottal volume velocity waveforms that have been estimated by inverse filtering acoustic speech pressure signals. The new technique, Parameter for Spectral and Amplitude Features of the Glottal Flow (PSA), combines two features of voice production, the AC value and the spectral decay of the glottal flow, both of which contribute to changes in vocal loudness. PSA yields a single parameter that characterizes the glottal flow in different loudness conditions. By analyzing voices of 8 speakers it was shown that the new parameter correlates strongly with the sound pressure level of speech.     

Nucleotide sequencing analysis of the 146-kilobase segment around the IkBL and MICA genes at the centromeric end of the HLA class I region

The biomechanics of medialization laryngoplasty are not well understood. An excised canine larynx model was used to test the effects of various sized silicon implants. The vocal fold length, position, and tension were measured. Medialization laryngoplasty did not affect vocal fold length. At the mid-membranous vocal fold, larger shims resulted in greater medialization and tension. Medialization laryngoplasty neither medialized nor stiffened the vocal process to resist lateralizing forces. We conclude that medialization laryngoplasty provides bulk and support for defects of the membranous region of the vocal fold, but does not appear to close a posterior glottal gap. The selection of a surgical procedure to treat glottal incompetence should take into account the unique biomechanical properties of the anterior (membranous vocal folds) and posterior (cartilaginous portion) glottis.     

Thrombus distribution and changes in aneurysm size following endovascular aortic aneurysm repair

Microvascular lesions, also called varices or capillary ectasias, in contrast to vocal fold polyps with telangiectatic vessels, are relatively small lesions arising from the microcirculation of the vocal fold. Varices are most commonly seen in female professional vocalists and may be secondary to repetitive trauma, hormonal variations, or repeated inflammation. Microvascular lesions may either be asymptomatic or cause frank dysphonia by interrupting the normal vibratory pattern, mass, or closure of the vocal folds. They may also lead to vocal fold hemorrhage, scarring, or polyp formation. Laryngovideostroboscopy is the key in determining the functional significance of vocal fold varices. Management of patients with a varix includes medical therapy, speech therapy, and occasionally surgical vaporization. Indications for surgery are recurrent hemorrhage, enlargement of the varix, development of a mass in conjunction with the varix or hemorrhage, and unacceptable dysphonia after maximal medical and speech therapy due to a functionally significant varix.     

Further studies of phonation threshold pressure in a physical model of the vocal fold mucosa

This paper reports results of further experimentation on a previously developed physical model of the vocal-fold mucosa [Titze et al., J. Acoust. Soc. Am. 97, 3080-3084 (1995)]. The effects of vocal-fold thickness, epithelial membrane thickness, and prephonatory glottal geometry on phonation threshold pressure were studied. Phonation threshold pressures in the range of 0.13 to 0.34 kPa were observed for an 11-mm-thick vocal fold with a 70-micron-thick "epithelial" membrane for different "mucosal" fluid viscosities. Higher threshold pressure was always obtained for thinner vocal folds and thicker membranes. In another set of experiments, lowest offset threshold pressure was obtained for a rectangular or a near-rectangular prephonatory glottis (with a glottal convergence angle within about +/- 3 degrees). It ranged from 0.07 to 0.23 kPa for different glottal half-widths between 2.0 and 6.0 mm. The threshold for more convergent or divergent glottal geometries was consistently higher. This finding only partially agrees with previous analytical work which predicts a lowest threshold for a divergent glottis. The discrepancy between theory and data is likely to be associated with flow separation from a divergent glottis.     

Critical review of phonosurgical methods in the treatment of sulcus vocalis

INTRODUCTION: Sulcus vocalis is an epithelial invagination along the free edge of the membranous vocal fold. It interferes with the glottic closure and vibration pattern. Sulcus vocalis provokes voice fatigue, hoarseness and breathiness, and it usually appears in association with hyperkinetic phonatory pattern. Hyperkinesis develops secondarily, due to the compensatory effort to overcome the deficiency in glottic closure. The treatment of sulcus vocalis is very difficult. Phonosurgery is used, and is followed by postoperative voice therapy. PHONOSURGICAL OPERATIONS: Various surgical techniques are used in the therapy of sulcus vocalis. Over a 10-year period we have operated on 1550 patients with benign lesion of the vocal folds, of whom only 11 had sulcus vocalis (0.7%). We carried out various surgical techniques. a) Excision of sulcus A longitudinal incision of mucosa is performed along the upper surface of the vocal fold, distant of the free edge. Mucosa is undermined caudally, and sulcus is detached from its base. Sulcus is then removed by surgical scissors. With this technique we could not provide physiological phonation and vibration pattern, in spite of an apparent improvement in the voice. b) "Slicing mucosa" technique This procedure was suggested by Pontes, and it also begins with a longitudinal incision followed by creation of inferiorly based slices of mucosa. c) Excision plus rhyroplasty Excision of sulcus is combined with thyroplasty type I in order to achieve medialization of the vocal fold. It can be used in cases with severe glottal gap in order to improve the results of excision. d) Implants Various materials were used in order to enlarge the mass of the vocal fold. In our patients, the results of this procedure were inferior as related to excision surgery. DISCUSSION: The surgical procedure which is safe and accepted by the majority of surgeons has not yet been at our disposal. The treatment of sulcus vocalis should start with voice therapy, which lasts as long as the patient shows a progress. Only then the surgical procedure can be discussed. We obtained the best results with the combination of excision and voice therapy. However, the surgeon and the patient must be aware that the treatment is demanding and long-lasting.     

Aerodynamic and acoustic characteristics of the adult African American voice

Laryngeal aerodynamic and acoustic characteristics of African American voice production were examined from vowel samples produced by ten adult female and ten adult male speakers. The data were compared with that for a control group consisting of ten adult female and ten adult male White speakers, matched for age, height, and weight. All measures were analyzed using Cspeech 4.0. Aerodynamic measurements, extracted from a glottal airflow waveform, included maximum flow declination rate, alternating glottal airflow, minimum glottal airflow, and airflow open quotient. Acoustic measures included fundamental frequency and sound pressure level. No significant mean differences between the African American and White speakers were found, except for maximum-flow declination rate. The White speakers produced significantly higher declination rates than the African American speakers. The factor of sex for the African American speakers was statistically significant for the measures of maximum-flow declination rate, alternating glottal airflow, open quotient, and fundamental frequency, consistent with the functioning of the White speakers. The results suggest that during vowel production, where the vocal tract is in a fairly static position, acoustic and aerodynamic characteristics for African American and White Speakers are comparable.     

Lubrication mechanism of the larynx during phonation: an experiment in excised canine larynges

To evaluate how the viscosity of the laryngeal mucus influences vocal fold vibration, two fluids of differing viscosity were applied separately to excised canine larynges and experimental phonation was induced. Vibration of the vocal folds was measured by use of a laryngostroboscope and an X-ray stroboscope. With the high viscosity fluid, the amplitude of vibration of the free edge and the peak glottal area was decreased while the open quotient was increased. Because the viscosity of this fluid affected the wave motion of the vocal fold mucosa, changes in viscosity of the mucus may be involved in causing such disorders as hoarseness, in the absence of apparent changes in the vocal folds themselves.     

Estimating phonation threshold pressure

Phonation threshold pressure (PTP) is the minimum subglottal pressure required to initiate vocal fold oscillation. Although potentially useful clinically, PTP is difficult to estimate noninvasively because of limitations to vocal motor control near the threshold of soft phonation. Previous investigators observed, for example, that trained subjects were unable to produce flat, consistent oral pressure peaks during/pae/syllable strings when they attempted to phonate as softly as possible (Verdolini-Marston, Titze, & Druker, 1990). The present study aimed to determine if nasal airflow or vowel context affected phonation threshold pressure as estimated from oral pressure (Smitheran & Hixon, 1981) in 5 untrained female speakers with normal velopharyngeal and voice function. Nasal airflow during /p/occlusion was observed for 3 of 5 participants when they attempted to phonate near threshold pressure. When the nose was occluded, nasal airflow was reduced or eliminated during /p/;however, individuals then evidenced compensatory changes in glottal adduction and/or respiratory effort that may be expected to alter PTP estimates. Results demonstrate the importance of monitoring nasal flow (or the flow zero point in undivided masks) when obtaining PTP measurements noninvasively. Results also highlight the need to pursue improved methods for noninvasive estimation of PTP.     

Loading changes in time-based parameters of glottal flow waveforms in different ergonomic conditions

The effects of prolonged (5 x 45 min) reading in different environmental and ergonomic conditions on time-based glottal waveform parameters of normal female and male subjects (n = 80) were studied. The exposure groups (n = 5 females and males per cell) consisted of eight combinations of the following factors: (1) normal (< 65 dB) or high (> 65 dB) speech output level; (2) sitting or standing posture; (3) low (25 +/- 5%) or high (65 +/- 5%) relative humidity of ambient air. Two rest (morning and noon) and three loading (two in the morning and one in the afternoon) samples were recorded and analyzed. The glottal waveforms were obtained by inverse filtering of the acoustical signal using an automatic method. The following time based parameters were analyzed from the estimate glottal flow waveform: (1) length of fundamental period; (2) open quotient; (3) speed quotient, and (4) closing quotient. The analysis was based on inverse filtering of the first stressed syllable of 'paappa' word repeated 3 x 5 times with normal, maximally soft and maximally loud phonation. Humidity was a significant factor in several instances. The interactions between gender and the loading factors were striking.     

Enhancement of electrolaryngeal speech by adaptive filtering

Artificial larynges provide a means of verbal communication for people who have either lost or are otherwise unable to use their larynges. Although they enable adequate communication, the resulting speech has an unnatural quality and is significantly less intelligible than normal speech. One of the major problems with the widely used Transcutaneous Artificial Larynx (TAL) is the presence of a steady background noise caused by the leakage of acoustic energy from the TAL, its interface with the neck, and the surrounding neck tissue. The severity of the problem varies from speaker to speaker, partly depending upon the characteristics of the individual's neck tissue. The present study tests the hypothesis that TAL speech is enhanced in quality (as assessed through listener preference judgments) and intelligibility by removal of the inherent, directly radiated background signal. In particular, the focus is on the improvement of speech over the telephone or through some other electronic communication medium. A novel adaptive filtering architecture was designed and implemented to remove the background noise. Perceptual tests were conducted to assess speech, from two individuals with a laryngectomy and two normal speakers using the Servox TAL, before and after processing by the adaptive filter. A spectral analysis of the adaptively filtered TAL speech revealed a significant reduction in the amount of background source radiation yet preserved the acoustic characteristics of the vocal output. Results from the perceptual tests indicate a clear preference for the processed speech. In general, there was no significant improvement or degradation in intelligibility. However, the processing did improve the intelligibility of word-initial non-nasal consonants.     

Prevalence of hypertension in patients with type II diabetes in referral versus primary care clinics

We report our clinical experience in managing a 59-year-old Italian male with Churg-Strauss syndrome (CSS) whose first clinical manifestation was a persistent dysphonia; the patient worked as a mechanic. Video-laryngostroboscopic examination revealed paresis of the right vocal fold with a reduction in adduction together with incomplete glottal closure. Spectrographic and spirometric tests both showed abnormal changes. Laryngeal electromyography revealed neurogenic damage of the right thyroarytenoid and crycoarytenoid muscles. Due to the appearance of typical signs of systemic involvement of CSS as a necrotizing vasculitis, the patient was admitted to the Rheumatology Unit of the University of Pisa. Histologic analysis of a skin lesion on the patient's foot confirmed the diagnosis. Treatment with 6-methylprednisolone quickly brought remission from systemic and laryngeal symptoms, as well as improvement in the results of video-laryngostroboscopic, spectrographic and laryngeal myographic tests.     

Vocal mechanics as the basis for phonosurgery

OBJECTIVE: A number of modifications in laryngoplastic phonosurgery have recently been proposed. This report is intended to clarify the concept on which the surgery should be based, vocal mechanics, for further rational development of the surgery. STUDY DESIGN: The results of various previous surgeries were compared. In an attempt to elucidate what makes the difference in the results, simulation of voice production was conducted with the use of excised larynges. METHODS: Excised larynges were mounted on a tube so as to be blown from below. Experimental variables in the model included the glottal area initially set, stiffness of the vocal folds, and subglottal pressure. The conditions under which the voice became hoarse were examined. RESULTS: The voice became hoarse under the following major conditions: 1) the initial glottal area exceeded a certain value, 2) stiffness was too high, and 3) the glottis was too tightly closed. Clinical representation for each condition was made, particularly for excessively tight glottal closure such as in spasmodic dysphonia. A new type of surgical treatment for spasmodic dysphonia, lateralization thyroplasty, was briefly reported, which restored the voice to normal without recurrence for 1 year at the time of this writing. CONCLUSIONS: A potential new type of laryngoplastic phonosurgery should be conformed to the mechanics of voice production. In treating dysphonia, it is often necessary to switch from etiologic or radical treatment, if infertile, to symptomatic treatment instead, at the level of mechanics.     

A precricoid swelling in a patient treated with Teflon injection in the vocal fold after idiopathic left vocal fold palsy

Vocal fold palsy is a cause of dysphonia. Due to incomplete glottic closure during phonation, patients with a unilateral vocal fold palsy present with a weak and breathy voice and recurrent aspiration. To lessen the clinical manifestations of unilateral vocal fold palsy, polytetrafluoroethylene (Teflon) paste is one agent which has been injected into the paraglottic region, thus causing the vocal fold to move more medially. One of the complications associated with Teflon paste injection is migration of the paste into the surrounding tissues. We present a patient with idiopathic left vocal fold palsy who underwent Teflon injection to the vocal fold and subsequently developed a precricoid nodule, mimicking a cartilaginous swelling.     

Comments on the myoelastic - aerodynamic theory of phonation

The myoelastic-aerodynamic theory of phonation has been quantified and tested with mathematical models. The models suggest that vocal fold oscillation is produced as a result of asymmetric forcing functions over closing and opening portions of the glottal cycle. For nearly uniform tissue displacements, as in falsetto voice, the asymmetry in the driving forces can result from the inertia of the air moving through the glottis. This inertia can in turn be enhanced or suppressed by supraglottal or subglottal vocal tract coupling. More obvious and pronounced asymmetries in the driving forces are associated with non-uniform vocal fold tissue displacements. These are combinations of normal tissue modes, and can result in vertical and horizontal phase differences along the surfaces, as observed in chest voice. The ranges of oscillation increase among various models as more freedom in the simulated tissue movement is incorporated. Of particular significance in initiating and maintaining oscillation are the vertical motions that facilitate coupling of aerodynamic energy into the tissues and allow tissue deformations under conditions of incompressibility. Vertical displacements also can have a significant on vocal tract excitation. Control of fundamental frequency of oscillation (FO) is basically myoelastic, partially as a result of deliberate or reflex adjustments of laryngeal muscles, and partially as a result of nonlinear tissue strain over the vibrational cycle. This places limits on the control of FO by subglottal pressure, and forces such control to be inseparably connected with vibrational amplitude, or less directly, with vocal intensity.     

Vocal fold scarring: current concepts and management

Scarring of the vocal folds can occur as the result of blunt laryngeal trauma or, more commonly, as the result of surgical, iatrogenic injury after excision or removal of vocal fold lesions. The scarring results in replacement of healthy tissue by fibrous tissue and can irrevocably alter vocal fold function and lead to a decreased or absent vocal fold mucosal wave. The assessment and treatment of persistent dysphonia in patients with vocal fold scarring presents both diagnostic and therapeutic challenges to the voice treatment team. The common causes of vocal fold scarring are described, and prevention of vocal fold injury during removal of vocal fold lesions is stressed. The anatomic and histologic basis for the subsequent alterations in voice production and contemporary modalities for clinical and objective assessment will be discussed. Treatment options will be reviewed, including nonsurgical treatment and voice therapy, collagen injection, fat augmentation, endoscopic laryngoplasty, and Silastic medialization.     

Vowel-related differences in laryngeal articulatory and phonatory function

The purpose of this investigation was to study the interaction between the supralaryngeal and laryngeal components of the speech mechanism by examining vowel-related effects for a variety of vocal fold articulatory and phonatory measures. Secondary issues were to determine if vowel-related differences were influenced by the nature of the speaking task or gender. Between-vowel differences in estimated subglottal air pressure, peak oral air flow, mean phonatory air flow, air flow near the termination of the vowel, electroglottograph cycle width (EGGW), fundamental frequency, and voice onset time were examined for men and women during syllable repetitions and sentence productions. Significant vowel-related differences were found for all of the measures except mean phonatory air flow, and generally were not influenced by speaking task or gender. Vowel-related effects for estimated subglottal air pressure, peak oral air flow, fundamental frequency, and VOT were consistent with some earlier studies. New findings included vowel-related differences in EGGW and air flow near the termination of the vowel. We propose a model that includes the contribution of mechanical forces, reflexive neural activity, and learned neural activity to explain vowel-related effects. When vowel height is varied, changes in laryngeal cartilage positioning and vocal fold and vocal tract tension appear to influence laryngeal articulatory and phonatory function.