Biomedical subjects

B R Gerratt

Publications and source records attributed to B R Gerratt.

18 recordsLinked to original sources

PubMed1992

Individual differences in voice quality perception.

Sixteen listeners (10 expert, 6 naive) judged the dissimilarity of pairs of voices drawn from pathological and normal populations. Separate nonmetric multidimensional scaling solutions were calculated for each listener and voice set. The correlations between individual listeners' dissimilarity ratings were low. However, scaling solutions indicated that each subject judged the voices in a reliable, meaningful way. Listeners differed more from one another in their judgments of the pathological voices (which varied widely on a number of acoustic parameters) than they did for the normal voices (which formed a much more homogeneous set acoustically). The acoustic features listeners used to judge dissimilarity were predictable from the characteristics of the stimulus sets: only parameters that showed substantial variability were perceptually salient across listeners. These results are consistent with prototype models of voice perception. They suggest that traditional means of assessing listener reliability in voice perception tasks may not be appropriate, and highlight the importance of using explicit comparisons between stimuli when studying voice quality perception.

Adult↗

PubMed1992

Videostroboscopy of human vocal fold paralysis.

Previous stroboscopic studies of human vocal cord paralysis have been infrequent and have lacked documentation of the site of lesion. In order to study human laryngeal paralysis, the recurrent and superior laryngeal nerves were infiltrated unilaterally with lidocaine hydrochloride in three human volunteers. Vagal paralysis was simulated by combined (superior and recurrent) infiltration in one volunteer. Additionally, 20 patients with untreated laryngeal paralysis were studied from the voice laboratory at UCLA. In addition to videostroboscopic analysis, photoglottography and electroglottography were performed and synchronized with the stroboscopic images. The most significant finding in stroboscopy of the paralyzed larynx was the asymmetry of traveling wave motion. The traveling wave on the normal vocal fold had a faster wave velocity that created a phase difference in the vibration of the two folds. The wave also traversed a greater distance along the vocal fold mucosa on the normal side. No patient or volunteer with untreated laryngeal paralysis had a symmetric traveling wave, either in superior or recurrent laryngeal nerve paralysis. Synchronization with glottography indicated that the differentiated electroglottographic waveform provides useful information about the timing of glottic opening and closure in states of asymmetric laryngeal vibration. Implications for future studies and for the diagnosis of laryngeal paralysis are discussed.

Adult↗

PubMed1992

Point-touch technique of botulinum toxin injection for the treatment of spasmodic dysphonia.

Intralaryngeal injections of botulinum toxin (Botox), under electromyographic guidance, have emerged as an effective treatment for adductor spasmodic dysphonia. To remain effective, these injections must be repeated every 3 to 9 months as the symptoms recur. One drawback to the current method is the need for electromyographic confirmation of needle placement into the thyroarytenoid muscle. This report describes an anatomic approach to Botox injection that requires only flexible nasopharyngeal endoscopy and careful evaluation of the anatomic landmarks. This technique has been used successfully on 13 patients, and objective pretreatment and posttreatment measures are reported.

Adult↗

PubMed1992

Effect of asymmetric vocal fold stiffness on traveling wave velocity in the canine larynx.

The vocal fold (VF) traveling wave is essential to normal voice production. The present investigation describes a new method to determine traveling wave velocity (TWV) in the in vivo canine phonatory model. This method synchronizes photoglottographic and electroglottographic waveforms with videostroboscopic images to determine the duration of time the traveling wave moves between two tattoos placed a known distance apart between the upper and lower margins of each VF. Using this method, we compared the TWV of a paralyzed VF with the TWV of the contralateral, electrically stimulated VF during phonation in two canines. In addition, the presumed VF stiffness asymmetry in the simulated acute recurrent laryngeal nerve paralysis state was confirmed by measuring Young's modulus of each VF. The results indicated that the TWV of the paralyzed VF averaged 55% of the TWV of the normal, stiffer VF when the glottal gap was small and entrainment occurred. This study demonstrated the feasibility of quantifying traveling wave motion in asymmetric VF stiffness disorders. The potential use of TWV in human beings as a target to optimize the phonosurgical results in asymmetric VF stiffness disorders is discussed.

Animals↗

PubMed1992

Laryngeal paralyses: theoretical considerations and effects on laryngeal vibration.

The neurological causes of vocal fold paralyses have been well documented. However, the effect of these disorders on laryngeal vibration is not well understood. A theoretical four-mass model of the larynx, based on the work of Ishizaka and Isshiki (1976) and Koizumi, Taniguchi, and Hiromitsu (1987), was developed and adapted to simulate laryngeal biomechanical behavior. The model was used to evaluate various states of asymmetric laryngeal vibration. Input parameters that relate observed laryngeal function and model simulation were developed. Laryngeal paralyses were simulated by their predicted effect on these parameters. Simulations were compared with available data on glottal vibration in laryngeal paralyses. Complex modes of vibration were seen with certain combinations of asymmetrical lower mass stiffness and initial glottal gap.

Computer Simulation↗

PubMed1990

Listener experience and perception of voice quality.

Five speech-language clinicians and 5 naive listeners rated the similarity of pairs of normal and dysphonic voices. Multidimensional scaling was used to determine the voice characteristics that were perceptually important for each voice set and listener group. Solution spaces were compared to determine if clinical experience affects perceptual strategies. Naive and expert listeners attended to different aspects of voice quality when judging the similarity of voices, for both normal and pathological voices. All naive listeners used similar perceptual strategies; however, individual clinicians differed substantially in the parameters they considered important when judging similarity. These differences were large enough to suggest that care must be taken when using data averaged across clinicians, because averaging obscures important aspects of an individual's perceptual behavior.

Clinical Competence↗

PubMed1990

Frequency, intensity, and target matching effects on photoglottographic measures of open quotient and speed quotient.

Measurements of Open Quotient (OQ) and Speed Quotient (SQ) were made from photoglottographic signals of normal male subjects during phonation. Samples were obtained at spontaneous levels of fundamental frequency and intensity, and at nine specified frequency/intensity combinations. OQ increased with fundamental frequency. OQ change was not significant for change in intensity and there was no significant interaction between frequency and intensity. Changes in SQ with variations of frequency and intensity were not significant. However, SQ did increase significantly when spontaneous phonation was compared to target matching phonation at similar frequency/intensity. Changes in both OQ and SQ across comfortable frequency and intensity ranges were relatively small in comparison to changes in OQ and SQ reported for pathological phonation.

Adult↗

PubMed1990

The effect of air flow and medial adductory compression on vocal efficiency and glottal vibration.

This study used an in vivo canine model to investigate the effects of varying vocal fold resistance by electrically stimulating the recurrent laryngeal nerve while monitoring medial adductory compression of the vocal folds, glottal airflow, and vocal intensity. The effects of increasing airflow on glottal vibration were also examined stroboscopically and by measurement of open quotient. The results indicated that increasing intensity by medial adductory compression was more efficient than by increasing airflow. Increasing airflow produced a significantly greater open quotient and vocal fold vibratory excursion.

Animals↗

PubMed1989

Office-based system for voice analysis.

There has been recent growing interest in the analysis of various electronically recorded signals as potential tools for objective assessment of vocal dysfunction. In the past, analysis of such signals required an expensive multitrack FM recorder, mainframe computer system, customized software, and significant time commitment. This report describes an adaptation of commercially available components that allow digital recording of multiple electronic signals, storage of data, and subsequent signal analysis using an inexpensive personal microcomputer system. Commercially available software for manipulation and examination signals is discussed as adapted for examination of glottographic and acoustic signals. The relatively inexpensive availability of similar computer systems will, hopefully, encourage assessment of the clinical applications of objective techniques of voice quality.

Analog-Digital Conversion↗

PubMed1989

Current and future horizons in laryngeal and voice research.

Voice dysfunction is associated with neuromuscular impairment of laryngeal control and is often difficult to diagnose by indirect examination of the larynx. The newer techniques, currently used in the UCLA-Veterans Administration Medical Center Laboratories, provide some methods that aid in the diagnosis of voice impairment by providing documented objective data. Illustrative case reports of disorders of neuromuscular dysfunction of the larynx are presented and future research needs and direction are discussed.

Aged↗

PubMed1989

The effect of recurrent laryngeal nerve stimulation on phonation in an in vivo canine model.

The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.

Animals↗

PubMed1988

An accurate method of Teflon injection using functional phonosurgery.

A technique for Teflon injection is described that allows the laryngologist to assess vocal fold vibration during general anesthesia. A tracheostomy tube fitted with a rostral air line allows translaryngeal airflow. During endoscopy with a bivalved laryngoscope, the cords are approximated manually. Vocal fold vibration is produced with the cords adducted. The precise site of defects in glottic closure is clearly seen and corrected with Teflon injection. In cases where standard Teflon injection has failed, utilization of this method has allowed substantial voice improvement. The ability to assess vibratory function of the vocal folds during direct suspension laryngoscopy enhances the precision of vocal fold augmentation techniques in difficult rehabilitation cases.

Aged↗

PubMed1988

Glottographic measures of vocal fold vibration: an examination of laryngeal paralysis.

Photoglottography and electroglottography were applied to groups of patients with recurrent laryngeal nerve paralysis, superior laryngeal nerve paralysis, and combined recurrent and superior laryngeal nerve paralyses of idiopathic causes. Individual patients with resection of the vagal nerve above the origin of the superior laryngeal nerve were also studied. Open Quotient and Speed Quotient were calculated from the photoglottography signals. Speed Quotient values significantly differentiated recurrent laryngeal nerve paralysis from idiopathic paralysis and superior laryngeal nerve paralysis, as well as from normal function. Data from patients with vagal resection clearly differentiated them from patients with recurrent laryngeal nerve paralysis. The measure of Open Quotient distinguished pathological phonation from normal, but was not as useful for separation of differing lesions. Electroglottography appeared to be less useful than photoglottography. The pathophysiology underlying the observed glottographic signals is discussed.

Adult↗

PubMed1987

Aphasic performance on a lexical decision task: multiple meanings and word frequency.

The lexical access of words varying in the number of meanings and frequency of occurrence was examined in fluent and nonfluent aphasic individuals and a control group of non-brain-damaged adults, using a lexical decision task. Fluent aphasic subjects performed similarly to nonfluent aphasic and normal subjects, showing that words with a high number of meanings and with a high frequency of occurrence were recognized as real words faster than words with few meanings or a low frequency of occurrence. While previous research has demonstrated that the number of meanings associated with a word exerts a powerful influence on the internal lexicon of normals, the results of this study suggest that brain damage resulting in aphasia does not disrupt this semantic organization.

Aged↗

PubMed1987

Laryngeal modeling: theoretical, in vitro, in vivo.

Because the larynx is situated anatomically in an area which is difficult to measure and visualize, theoretical, in vitro, and in vivo models are used in laryngeal research. Vocal fold vibration was studied in anesthetized dogs, while electrically stimulating independently the superior and recurrent laryngeal nerves under conditions of constant airflow. Photoglottographic (PGG), electroglottographic (EGG), and subglottic pressure signals were obtained while stroboscopically photographing the larynx. Specific points along PGG, EGG, and subglottic pressure waveforms were correlated with laryngeal events which occurred during vibration. The canine larynx, in an experimentally produced phonatory mode, vibrates in a two mass (upper and lower margin) system and appears comparable to modal human voice production. The recorded glottographic waveforms from experimentally produced phonation in the canine are similar to signals recorded from humans. However, observed differences can be related to anatomic differences.

Animals↗

PubMedDate not supplied

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model.

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Animals↗

PubMedDate not supplied

Synchronizing videostroboscopic images of human laryngeal vibration with physiological signals.

PURPOSE: This report describes a new system that permits the precise correlation of videostroboscopic images with corresponding physiological measures, such as glottography and subglottic pressure. METHOD: A healthy volunteer had unilateral vocal cord paralysis induced by infiltrating local anesthesia into the recurrent and superior laryngeal nerve. Vocal-fold vibrations were monitored by photoglottography (PGG) and electroglottography (EGG). Analog signals from the EGG and PGG were synchronized with the video and correlated. RESULTS: The method described permits images to be sampled throughout sustained phonation. This technique allows study of events during glottic vibration. Results obtained have been in close agreement with previous studies that correlate the vocal-fold morphology to glottographic signal using other methods. This technique is inexpensive in comparison with high-speed filming. The main disadvantage of this method is related to the limitations of stroboscopy.

Adult↗

PubMedDate not supplied

Laryngeal configuration associated with glottography.

This report describes a method for testing and confirming the relationship of glottography to the vibratory movements of the vocal folds. According to this method, vocal fold movement is monitored by photoglottography (PGG) and electroglottography (EGG) as photographs are taken using a 80-microsecond flash provided by a laryngostroboscope. The flash is recorded as an impulse on the PGG waveform, indicating the location on the glottographic signals of the corresponding single frame photograph. We then present a test case, in which various vocal fold configurations are documented, demonstrating that the timing of glottal events can be correlated to glottographic signals by this method.

Adult↗