Mean Subglottal Pressure Research Articles

Predictive value of strobovideolaryngoscopy, acoustic and aerodynamic measures in the prognosis of temporally unilateral vocal fold paralysis after thyroidectomy

Objective:To investigate the strobovideolaryngoscopy, acoustic and aerodynamic characteristics of transient unilateral vocal ford paralysis（UVFP） after thyroidectomy. Methods:A retrospective analysis was made of 11 patients with temporary UVFP after thyroidectomy who were treated in Department of Otolaryngology and Head and Neck Surgery, Sun Yat-sen Memorial Hospital, Sun Yat-sen University from January 2013 to March 2021; 8 patients with permanent UVFP after thyroidectomy during the same period were included as a control group. The differences in baseline strobovideolaryngoscopy, acoustic and aerodynamic measures were compared between the two groups. Results:The tones of patients with temporary UVFP after thyroidectomy were all normal, and the proportions of abnormal vocal fords（vocal ford bowing, atrophy, and shortening）, ventricular adduction and glottic insufficiency were significantly lower than those of permanent UVFP patients; arytenoid cartilage stability and height mismatch of vocal ford tended to be better than permanent UVFP. The maximal phonation time（MPT） in patients with temporary UVFP was （8.5±4.1） s, which was significantly longer than （3.9±2.1） s in patients with permanent UVFP; fundamental frequency, mean airflow（MeAF） and mean subglottic pressure（SGP） were better in temporary UVFP than those in patients with permanent UVFP, but the difference did not reach statistical significance. Conclusion:None and mild glottic insufficiency, normal tone, ventricular adduction, and vocal ford appearances without vocal fold bowing, atrophy, and shortening, can be served as the predictors for the early recovery of vocal ford movement in temporary UVFP after thyroidectomy. The MPT less than 4 s, and MeAF, and SGP remarkably increased is the predictor of poor prognosis for vocal ford recovery.

Estimation of Subglottal Pressure, Vocal Fold Collision Pressure, and Intrinsic Laryngeal Muscle Activation From Neck-Surface Vibration Using a Neural Network Framework and a Voice Production Model.

The ambulatory assessment of vocal function can be significantly enhanced by having access to physiologically based features that describe underlying pathophysiological mechanisms in individuals with voice disorders. This type of enhancement can improve methods for the prevention, diagnosis, and treatment of behaviorally based voice disorders. Unfortunately, the direct measurement of important vocal features such as subglottal pressure, vocal fold collision pressure, and laryngeal muscle activation is impractical in laboratory and ambulatory settings. In this study, we introduce a method to estimate these features during phonation from a neck-surface vibration signal through a framework that integrates a physiologically relevant model of voice production and machine learning tools. The signal from a neck-surface accelerometer is first processed using subglottal impedance-based inverse filtering to yield an estimate of the unsteady glottal airflow. Seven aerodynamic and acoustic features are extracted from the neck surface accelerometer and an optional microphone signal. A neural network architecture is selected to provide a mapping between the seven input features and subglottal pressure, vocal fold collision pressure, and cricothyroid and thyroarytenoid muscle activation. This non-linear mapping is trained solely with 13,000 Monte Carlo simulations of a voice production model that utilizes a symmetric triangular body-cover model of the vocal folds. The performance of the method was compared against laboratory data from synchronous recordings of oral airflow, intraoral pressure, microphone, and neck-surface vibration in 79 vocally healthy female participants uttering consecutive /pæ/ syllable strings at comfortable, loud, and soft levels. The mean absolute error and root-mean-square error for estimating the mean subglottal pressure were 191 Pa (1.95 cm H2O) and 243 Pa (2.48 cm H2O), respectively, which are comparable with previous studies but with the key advantage of not requiring subject-specific training and yielding more output measures. The validation of vocal fold collision pressure and laryngeal muscle activation was performed with synthetic values as reference. These initial results provide valuable insight for further vocal fold model refinement and constitute a proof of concept that the proposed machine learning method is a feasible option for providing physiologically relevant measures for laboratory and ambulatory assessment of vocal function.

Estimation of Subglottal Pressure From Neck Surface Vibration in Patients With Voice Disorders.

Purpose Given the established linear relationship between neck surface vibration magnitude and mean subglottal pressure (Ps) in vocally healthy speakers, the purpose of this study was to better understand the impact of the presence of a voice disorder on this baseline relationship. Method Data were obtained from participants with voice disorders representing a variety of glottal conditions, including phonotraumatic vocal hyperfunction, nonphonotraumatic vocal hyperfunction, and unilateral vocal fold paralysis. Participants were asked to repeat /p/-vowel syllable strings from loud-to-soft loudness levels in multiple vowel contexts (/pa/, /pi/, /pu/) and pitch levels (comfortable, higher than comfortable, lower than comfortable). Three statistical metrics were computed to analyze the regression line between neck surface accelerometer (ACC) signal magnitude and Ps within and across pitch, vowel, and voice disorder category: coefficient of determination (r 2), slope, and intercept. Three linear mixed-effects models were used to evaluate the impact of voice disorder category, pitch level, and vowel context on the relationship between ACC signal magnitude and Ps. Results The relationship between ACC signal magnitude and Ps was statistically different in patients with voice disorders than in vocally healthy controls; patients exhibited higher levels of Ps given similar values of ACC signal magnitude. Negligible effects were found for pitch condition within each voice disorder category, and negligible-to-small effects were found for vowel context. The mean of patient-specific r 2 values was .63, ranging from .13 to .92. Conclusions The baseline, linear relationship between ACC signal magnitude and Ps is affected by the presence of a voice disorder, with the relationship being participant-specific. Further work is needed to improve ACC-based prediction of Ps, across treatment, and during naturalistic speech production.

Objective Characterization of Phonation Type Using Amplitude of Flow Glottogram Pulse and of Voice Source Fundamental

Phonation type, a phonatory dimension ranging from hypofunctional/breathy to hyperfunctional/pressed, is important both from a clinical and acoustical point of view; hyperfunctional voice can lead to voice disorders and hypofunctional voice reduces text intelligibility. Five male singers sang diminuendo sequences of the syllable /pae/ and three of them also produced speech or singing samples with different phonation types which were rated for phonatory pressedness by a panel of voice experts. The sequences were analyzed by inverse filtering and the associated subglottal pressures were estimated as the oral pressures during the /p/ occlusion. The results showed strong quasi-linear correlations between the peak-to-peak amplitude of the flow glottogram (henceforth pulse amplitude) and mean subglottal pressure, mean airflow, and the level difference between the first and second voice source partials L1-L2. These correlations were found to vary systematically with phonation type. Regardless of phonation type, the correlation between the pulse amplitude and the amplitude of the voice source fundamental frequency was very close to 1.0. The level difference between the first and second spectrum partials L1-L2 in narrow-band long-term-average spectra of speech and singing was found to vary systematically with phonation type in a manner related to voice experts' ratings of perceived degree of pressedness. The findings support the assumption that the combination of subglottal pressure and level of the voice source fundamental is useful for an objective measure of phonation type.

Voice outcome indicators for unilateral vocal fold paralysis surgery: a review of the literature.

There is no consensus on which voice outcome indicators (VOIs) should be used to compare the merits of the various surgical treatments for unilateral vocal fold paralysis (UVFP). Authors performed a literature review to identify which VOIs are most frequently used and most relevant, in terms of significant change in pre- and post-operative measurements, to assess UVFP surgical treatments. A Medline/Pubmed literature review was performed and the most frequently used VOIs were identified using a Pareto diagram. For these most frequently used VOI's, the number of studies that showed a statistically significant change in pre- and post-operative results were compared to the total number of studies foundusing that same VOI, this portion was expressed in percent. This percentage was defined as the "percentage of significance" and used to assess changes of each VOI. Eleven VOIs were identified using the Pareto analysis. These were, in decreasing order of frequency of citation: maximum phonation time (MPT), jitter, Shimmer, video-stroboscopic examination, noise to harmonic ratio (NHR/HNR), mean air flow (MeAF), fundamental frequency (F0), "Infrequent Perceptional Scales", GRBAS scale, mean subglottic pressure (MSGP). MPT, MeAF, factor G of GRBAS-I, Jitter, shimmer and VHI-30 had respective "percentage of significance" of 90, 86, 85, 74, 68 and 64%, respectively. The results indicate that MPT, MeAF and GRBAS-I, represent the top-three most frequently used and the most relevant VOIs in terms of "percentage of significance". VHI-30 showed a relatively low rate of use and low "percentage of significance". The role of Jitter and Shimmer remains unclear. Finally, MSGP and the F0 appear to be less relevant VOIs for the evaluation of UFVP surgical treatments in terms of significant change in pre- and post-operative measurements.

Physical parameter estimation from porcine ex vivo vocal fold dynamics in an inverse problem framework.

This study presents a framework for a direct comparison of experimental vocal fold dynamics data to a numerical two-mass-model (2MM) by solving the corresponding inverse problem of which parameters lead to similar model behavior. The introduced 2MM features improvements such as a variable stiffness and a modified collision force. A set of physiologically sensible degrees of freedom is presented, and three optimization algorithms are compared on synthetic vocal fold trajectories. Finally, a total of 288 high-speed video recordings of six excised porcine larynges were optimized to validate the proposed framework. Particular focus lay on the subglottal pressure, as the experimental subglottal pressure is directly comparable to the model subglottal pressure. Fundamental frequency, amplitude and objective function values were also investigated. The employed 2MM is able to replicate the behavior of the porcine vocal folds very well. The model trajectories' fundamental frequency matches the one of the experimental trajectories in [Formula: see text] of the recordings. The relative error of the model trajectory amplitudes is on average [Formula: see text]. The experiments feature a mean subglottal pressure of 10.16 (SD [Formula: see text]) [Formula: see text]; in the model, it was on average 7.61 (SD [Formula: see text]) [Formula: see text]. A tendency of the model to underestimate the subglottal pressure is found, but the model is capable of inferring trends in the subglottal pressure. The average absolute error between the subglottal pressure in the model and the experiment is 2.90 (SD [Formula: see text]) [Formula: see text] or [Formula: see text]. A detailed analysis of the factors affecting the accuracy in matching the subglottal pressure is presented.

Modeling flow through the posterior glottal gap

The BGSU three mass model of phonation incorporates a posterior glottal gap. The airflow through the gap is governed by a simple hydraulic formula. The current study compares predictions of the gap size to the DC flow of three human subjects over two pitches at normal loudness. This work also explores the importance of the posterior gap by comparing extensive human mean subglottal pressure—mean flow—vocal process adduction data (from one subject) with the behavior of the model. The relation between glottal gap size to the DC flow for the three subjects was exceptionally strong (R2 = 0.99). The relatively linear pressure-flow relationships at specific adduction values for the human data are hypothesized to be mimicked by the model, with a reasonable relationship to the size of the posterior glottal gap. [Work support from NIH.]

Reinnervation for Vocal Fold Paralysis: Results in Children

Objective: 1) Exhibit long-term follow-up results of patients with unilateral vocal fold immobility who underwent ANSA reinnervation of the recurrent laryngeal nerve. 2) Demonstrate the appropriate studies that should be performed at the time of follow-up. Method: Retrospective review in a tertiary care otolaryngology practice. Four patients with symptomatic unilateral vocal fold paralysis who underwent recurrent laryngeal nerve reinnervation by a single surgeon were reviewed between September 2005 and December 2011. Postoperative measurements were obtained, both subjective (voice questionnaire) and objective (acoustic measurements and aerodynamics). Results: The study group included 3 girls and 1 boy ages 2 to 12 years. Mean follow-up time was 4.25 years. Causes for vocal fold paralysis were cardiac surgery (3) and skull base neoplasm (1). Voice questionnaire results (0 = severely abnormal, 100 = normal) were 100 in 2 patients, 98 in 1 patient, and 96 in 1 patient indicating a high level of satisfaction postoperatively in all patients. Mean maximum phonation time was 7.7 seconds, mean s/z ratio was 2.15, and mean subglottal pressure was 8.8 cm H2O. Conclusion: Children who undergo ANSA reinnervation of the recurrent laryngeal nerve have normal or near normal subjective voice scores. Objective scores may not reflect the same change. In this population, it may be beneficial for the practitioner to rely upon subjective measures rather than objective measures to determine treatment success.

Phonation threshold pressure estimation using electroglottography in an airflow redirection system

The present study proposed to estimate phonation threshold pressure (PTP) noninvasively using airflow redirection into a pneumatic capacitance system. Prospective study. Subjects phonated into the device, which interrupts airflow mechanically and redirects the flow into a pneumatic capacitor. Five interruptions were effected per trial. PTP was estimated as the difference between subglottal pressure (SGP) and transglottal pressure at phonation offset. The novel method was tested for consistency in 20 normal human subjects at low (75 dB) and high (85 dB) sound pressure levels. The device was tested for validity on a tracheotomy patient. Mean SGP was 9.02 +/- 3.27 cm H(2)O, and mean PTP was 3.68 +/- 1.41 cm H(2)O. Intrasubject coefficient of variation, a measure of intrasubject consistency, was 0.33 +/- 0.23. Statistically significant differences existed between the means of SGP but not PTP at 75 dB and 85 dB. The correlation coefficient between accepted and experimental SGP in a tracheotomy patient was 0.947 (P < .001). Measurements corresponded well to previously reported values, and intrasubject variability was low, indicating the device was consistent. Testing on a tracheotomy patient demonstrated validity. More research is needed to determine the sensitivity and specificity of the device in differentiating between normal and pathological voices. This device may have clinical application as a noninvasive and reliable method of estimating PTP and indicating that laryngeal health is likely abnormal.

Aerodynamic Measurements: Normative Data for Children Ages 6:0 to 10:11 Years

Normative measures of open quotient, speed quotient, maximum flow declination rate (MFDR), and subglottal pressure were determined for 75 children between the ages of 6 years 0 months and 10 years 11 months. The participants produced a sustained /a/ at low, comfort, and high pitches for a minimum of 5 seconds, and five to seven repetitions of /pa/ at low, comfort, and high pitches. No statistically significant differences were found in the mean measures of any aerodynamic variables (open quotient, speed quotient, maximum flow declination rate, subglottal pressure) between the frequency levels (low, comfort, high pitches). Also, no strong evidence (P > .05) exists that age or sex effect differed between the frequency levels (low, comfort, high) for any of the aerodynamic measures. For /a/ response tasks, mean open quotient measures increased slightly from low to comfort frequency and from comfort to high frequency. Mean speed quotient measures showed minimal differences between low and comfort frequency, with decreased mean measures for high frequency. Mean MFDR measures increased from low to comfort frequency and from comfort to high frequency. Mean subglottal pressure measures increased slightly from low to comfort frequency and from comfort to high frequency.

Source spectra for excised and latex phonatory models

An excised larynx model and a latex physical model were used to study acoustic spectra of the phonatory source as a function of subglottal pressure, glottal adduction, and vocal-fold length. A supraglottal vocal tract was not used, indicating that the acoustic signal corresponded to the output glottal flow. Each model was mounted over an -inch tracheal tube through which flowed pressurized, heated, and humidified air. The subglottal pressure and EGG signal (excised model) were recorded on a personal computer. The mean flow rate, mean subglottal pressure, and SPL were recorded manually, and adduction was specified by the use of interarytenoid shims. The output audio signals from the larynx models were recorded on a DAT recorder. Spectral information of the audio signal was obtained via FFT analysis (Matlab). Preliminary data indicate that the spectral slope did not have a constant dB/octave rate, and spectral slope had a primary dependence on subglottal pressure and a secondary dependence on adduction. Other acoustic details and the differences between the two models will be discussed. [Work supported by NIDCD Grant Number DC03566.]

Active upper airway closure during induced central apneas in lambs is complete at the laryngeal level only.

We tested the hypotheses that active upper airway closure during induced central apneas in nonsedated lambs 1). is complete and occurs at the laryngeal level and 2). is not due to stimulation of the superior laryngeal nerves (SLN). Five newborn lambs were surgically instrumented to record thyroarytenoid (TA) muscle (glottal constrictor) electromyographic (EMG) activity with supra- and subglottal pressures. Hypocapnic and nonhypocapnic central apneas were induced before and after SLN sectioning in the five lambs. A total of 174 apneas were induced, 116 before and 58 after sectioning of the internal branch of the SLN (iSLN). Continuous TA EMG activity was observed in 88% of apneas before iSLN section and in 87% of apneas after iSLN section. A transglottal pressure different from zero was observed in all apneas with TA EMG activity, with a mean subglottal pressure of 4.3 +/- 0.8 cmH2O before and 4.7 +/- 0.7 cmH2O after iSLN section. Supraglottal pressure was consistently atmospheric. Sectioning of both iSLNs had no effects on the results. We conclude that upper airway closure during induced central apneas in lambs is active, complete, and occurs at the glottal level only. Consequently, a positive subglottal pressure is maintained throughout the apnea. Finally, this complete active glottal closure is independent from laryngeal afferent innervation.

Analysis of Voice and Quantitative Measurement of Glottal Gap After Thyroplasty Type I in the Treatment of Unilateral Vocal Paralysis

Thyroplasty type I is one of several surgical treatments in which improving the voice of unilateral vocal fold paralysis is the ultimate objective. The goal of the surgery is the medialization of the paralyzed vocal fold. The purpose of this study is to evaluate the effectiveness of thyroplasty type I through acoustical analysis, aerodynamic measures, and quantitative videostroboscopic measurements. We report on 20 patients with unilateral vocal cord paralysis who underwent thyroplasty type I. We performed preoperative and postoperative video image analysis (normalized glottal gap area) and computer-assisted voice analysis (fundamental frequency, jitter, shimmer, noise-to-harmonic ratio, mean phonation time, mean flow rate, mean subglottic pressure) in all patients. The glottal gap was significantly reduced after thyroplasty type I. Postoperative voice quality was characterized by an improved pitch and amplitude pertubation (jitter and shimmer), phonation time (mean phonation time), and subglottic pressure (mean subglottic pressure). Thyroplasty type I is an effective method for regaining glottal closure and vocal function.

Aerodynamic profiles of a hemilarynx with a vocal tract.

The pressure-flow relationship was examined in excised canine and human larynges with and without a vocal tract. Canine and human larynges were prepared and cut in the midsagittal plane from the top to about 10 mm below the vocal folds. The right half was removed and replaced with an acrylic plate. The vocal tract was simulated initially with a 15-cm plastic tube and later with a vocal tract model with an area function resembling "ah." Simultaneous recordings were made of the glottal pressure, mean subglottal pressure, and average airflow at various levels of adduction. Preliminary data indicated that the pressure-flow relationships were similar to those of a full larynx and were almost linear. The addition of the vocal tract increased the glottal resistance by moving these pressure-flow lines to the lower-flow and higher-pressure region. The human larynx appears to phonate more easily than the canine larynx on the laboratory bench and has lower phonation threshold pressures.

Aerodynamic measurements of patients with Parkinson's disease.

Patients with Parkinson's disease commonly complain of voice dysfunction. Most of these complaints can be attributed to the known muscular control disorders that occur with Parkinson's disease. However, the manifestations of Parkinson's disease muscular dysfunction on parameters of phonation such as airflow, laryngeal resistance, and subglottal pressure necessary to sustain phonation have not been reported. The purpose of this study was to examine the aerodynamic characteristics of flow, laryngeal resistance, and phonation pressure threshold in a heterogeneous population of patients with Parkinson's disease who had varying voice complaints and to compare the data to similar studies for human subjects who have no voice complaints. The studies used a noninvasive method of detecting flow and acoustic signal from the lips, oral cavity and nose during phonation and used an external flow interruption technique to estimate subglottal pressure and phonation threshold pressure. About one third of the patients could not produce phonation at regular and loud intensities that were comfortable for normal subjects. The mean subglottal pressure (SGP) of patients with Parkinson disease who could produce 3 levels of intensity comparable to normal subjects was significantly higher than the mean SGPs for normal subjects for the same intensities of vocal production. The mean flow rates measured from patients with Parkinson's disease at the same 3 intensities of phonation was not significantly greater than in normal subjects. This indicated that the mean laryngeal resistance calculated for patients with Parkinson's disease was notably and significantly greater than mean laryngeal resistance calculated for normal subjects at the same intensity levels. The mean vocal efficiency (VE) for normal subjects was not significantly different than the mean VE for patients with Parkinson's disease, because greater pressure was used to generate similar flow and acoustic energy. These findings correlate with the perception of patients with Parkinson's disease that they are working harder to produce phonation. The observation of notably greater laryngeal resistance and phonation threshold pressure in patients with Parkinson's disease suggests that further studies of the glottic aperture in patients with Parkinson' disease may be useful for understanding how this common motor disorder disturbs phonation.

Effects of vocal tract on aerodynamics of hemilarynx

Pressure-flow relationship was examined in the excised canine and human larynges with and without vocal tract. Canine and human larynges were prepared and cut in the midsaggital plane from the top to about 10 mm below the vocal folds. The right half was removed and replaced with a Plexiglas plate with imbedded pressure taps along the medial surface. The thyroid cartilage was glued to the plate and the arytenoid was pressed against the plate with a two-pronged probe for adduction control. The vocal tract was simulated with a 15-cm plastic tube of 25-mm diameter. Simultaneous recordings were made of the glottal pressure, mean subglottal pressure, and average airflow at various levels of adduction. Glottal adduction was controlled mechanically by inserting shims of various sizes. Oscillation was generated by the flow of heated and humidified air through the glottis. Preliminary data indicate that the pressure-flow relationships are similar to those of full larynx and are almost linear. The addition of the vocal tract increased the glottal resistance by moving these pressure-flow lines to the lower flow and higher-pressure region. The human larynx appears to phonate easier on the bench and has lower phonation threshold pressure. [Work supported by NIDCD grant DC03566.]

Effects of lung volume on the glottal voice source.

According to experience in voice therapy and singing pedagogy, breathing habits can be used to modify phonation, although this relationship has never been experimentally demonstrated. In the present investigation we examine if lung volume affects phonation. Twenty-four untrained subjects phonated at different pitches and degrees of vocal loudness at different lung volumes. Mean subglottal pressure was measured and voice source characteristics were analyzed by inverse filtering. The main results were that with decreasing lung volume, the closed quotient increased, while subglottal pressure, peak-to-peak flow amplitude, and glottal leakage tended to decrease. In addition, some estimates of the amount of the glottal adduction force component were examined. Possible explanations of the findings are discussed.

A comparison of subglottal and intraoral pressure measurements during phonation

Intraoral pressure and subglottal pressure, derived from tracheal puncture, were recorded with the electroglottographic signal for one normal speaking male during phonation. The mean subglottal pressure for vowels was also estimated by interpolating the intraoral pressure from surrounding /p/occlusions. The pressure measurements were highly correlated (r = 0.98) and there were small pressure value differences (on average < 2%). The effects of varying speech rate and mode of phonation on the pressure measurements are discussed. A decrease in pressure from the mean subglottal pressure for the open phase and an increase for the closed phase was found during the glottal vibratory cycles.

声帯ポリープと早期声門癌における発声機能の比較

Aerodynamic parameters during optimal easy phonation were compared among 6 patients with vocal polyps, 32 patients with glottic cancer (T1 and T2) and 9 normal subjects.Subglottal pressures (cmH2O) directly extracted by the miniatured pressure tranceducer through the glottis, mean air flow (ml/sec), pitch (Hz) and intensity (dB) of voices, glottal resistance (cmH2O/l/sec), subglottal power (×106 erg/sec), and laryngeal efficiency were obtained with the use of PS-77phonatory equipment and the computerized phonatory system PI-100.The cases with vocal polyps presented with slightly high values of mean subglottal pressure (the mean value of 9.0cmH2O) and glottal resistance (the mean value of 38.5cmH2O/l/sec) and glottal power 3 times greater than that of the normal subjects. The mean value of laryngeal efficiency was about a half level of that in the normal subjects. In the cases of glottic cancer, the subglotal pressures were inceased to the mean value of 11.6 cmH2O in Tla, 21.7cmH2O in Tlb and 25.7cmH2O in T2 cases respectively. The Glottal resistance and subgottal power were significantly increased by as the T stage became advanced. In contrast, the laryngeal efficiencies decreased as the T stage was advanced : the mean value of 1.27 in T1a, 0.50 in T1b, and 0.25 in T2 cases.

Selective laryngeal neurotomy and the control of phonation by the echolocating bat,Eptesicus

1. The effect, on the subglottic pressure and on the emitted orientation sounds, of selectively cutting nerves to various laryngeal muscles of the Big Brown Bat,Eptesicus fuscus, was studied. 2. Bilateral inferior laryngeal neurotomy caused no change in the repetition rate, duration, initial frequency or bandwidth of downward sweeping frequency modulated (FM) pulses, but after this treatment mean subglottic pressure at pulse onset was lowered 8 to 16 cm H2O and the mean peak pulse intensity was reduced 4 to 5 dB. The relationship of subglottic pressure to the bandwidth of the FM sweep was also altered (Table 1, Figs. 1, 2, 3). 3. Inferior laryngeal neurotomy also caused the bat to produce atypical rising FM pulses which began at about 20 kHz and swept upward almost one octave (Table 1, Fig. 2). 4. Total bilateral superior laryngeal neurotomy eliminated most of the FM and reduced the fundamental frequency to 7.9 kHz with multiple harmonics (Fig. 4). Pulse duration became highly variable and the peak sound pressure level (SPL) dropped 7 to 13 dB (Table 2). The correlation between subglottic pressure and pulse SPL was also eliminated. 5. Bilateral section of only the caudal branch of the superior laryngeal nerve reduced the fundamental frequency of the pulses to 10 kHz and eliminated most of the frequency modulation. Pulse SPL was reduced about 10 dB, but pulse onset subglottic pressure remained correlated with the maximum SPL (Table 2). 6. Paralysis of the tongue by bilateral section of the hypoglossal nerves distal to the thyrohyoid twigs had no detectable effect on the downward sweeping FM pulses, but caused the bats to also emit long duration pulses whose frequency rose and fell in a sinusoidal fashion (Figs. 5, 6). 7. The muscular control of pulse frequency and intensity is discussed in the light of these data. The aberrant rising FM after section of the inferior laryngeal nerves and sigmoid pulses after hypoglossal neurotomy can be understood as the result of timing errors in the opening and/or closing of the glottis relative to the contraction-relaxation cycle of the cricothyroid muscles.