Ambulatory Phonation Monitoring Using Wireless Bluetooth Earphones

OBJECTIVE

Ambulatory phonation monitoring (APM) has a long evolving history. Current devices mostly use a contact microphone or accelerometer over the anterior neck, limiting its general acceptance outside of academic purposes. This study applied wireless Bluetooth earphones to receive voice signals. We also designed a mobile App with personalized AI model to identify phonation segments.

STUDY DESIGN

Proof of concept study.

SETTING

Acoustic laboratory.

METHODS

The materials comprised 1-hour audio files from seven teachers recorded in the classroom. The first 5minutes were used to train the personalized SpeechDetection models using deep neural networks. Another six segments (30 seconds each) were selected for assessing the accuracy of this APM system using two parameters: (1) speech intensity, which was compared to the gold standard measured by CLIO 12, a professional system for voice recording, and (2) phonation segments, which was compared with manual labeling.

RESULTS

The training accuracy of the SpeechDetection model ranged from 91.2% to 98.5%, with a mean of 95.4%. The testing accuracy for detecting phonation segments ranged from 88.4% to 97.0% (mean: 91.5%). The Kappa value of consistency ranged from 0.710 to 0.931 (mean: 0.813, P < 0.001 for all seven participants). After linear calibration, the accuracy of measuring speech intensity ranged from 0.846 to 0.927 (mean: 0.885, P < 0.001, Pearson correlation coefficient).

CONCLUSIONS

The study results demonstrated that a novel APM system using wireless earphones with mobile apps can accurately measure phonation segments and speech intensity for teachers in the classrooms. Further experiments under different environments with more participants are mandatory before extrapolating this system to real-world use cases.

LEVEL OF EVIDENCE

N/A.

Quantifying the Occupational Voice Use of Teachers

Purpose

The teaching profession is a high-voice use occupation at elevated risk for developing voice disorders. Continued research on teachers' vocal demands is necessary to advocate for and establish vocal health programs. This study quantified ambulatory vocal dose measures for teachers during both on- and off-work periods, comparing their occupational voice use to that in other studies that have reported percent phonation ranging from 17% to 30%.

Method

Participants included 26 full-time, female school teachers between 23 and 55 years of age across multiple grades and subjects, including individuals with and without a voice disorder. Ambulatory voice data were collected from weeklong voice monitoring that recorded phonatory activity through anterior neck-surface vibration. Three vocal dose measures-time, cycle, and distance doses-were computed for each participant for three time periods: on-work weekdays, off-work weekdays, and off-work weekend days.

Results

The teachers' average percent phonation was 16.2% on-work weekdays, 8.4% off-work weekdays, and 8.0% off-work weekend days. No statistically significant differences for vocal dose measures were found between off-work weekdays and weekend days. Overall, all vocal dose measures were approximately 2 times higher during work relative to off-work time periods.

Conclusions

This study provides values for vocal dose measures for school teachers using ambulatory voice-monitoring technology. The vocal demands of this particular teacher sample and voice activity detection algorithm are potential factors contributing to percent phonation values on the lower end of the range reported in the literature. Future work is needed to continue to understand occupational voice use and its associated risks related to voice health, with the ultimate goal of preventing and managing voice disorders in individuals engaged in high-risk occupations.

Ambulatory Monitoring of Subglottal Pressure Estimated from Neck-Surface Vibration in Individuals with and without Voice Disorders

The aerodynamic voice assessment of subglottal air pressure can discriminate between speakers with typical voices from patients with voice disorders, with further evidence validating subglottal pressure as a clinical outcome measure. Although estimating subglottal pressure during phonation is an important component of a standard voice assessment, current methods for estimating subglottal pressure rely on non-natural speech tasks in a clinical or laboratory setting. This study reports on the validation of a method for subglottal pressure estimation in individuals with and without voice disorders that can be translated to connected speech to enable the monitoring of vocal function and behavior in real-world settings. During a laboratory calibration session, a participant-specific multiple regression model was derived to estimate subglottal pressure from a neck-surface vibration signal that can be recorded during natural speech production. The model was derived for vocally typical individuals and patients diagnosed with phonotraumatic vocal fold lesions, primary muscle tension dysphonia, and unilateral vocal fold paralysis. Estimates of subglottal pressure using the developed method exhibited significantly lower error than alternative methods in the literature, with average errors ranging from 1.13 to 2.08 cm H₂O for the participant groups. The model was then applied during activities of daily living, thus yielding ambulatory estimates of subglottal pressure for the first time in these populations. Results point to the feasibility and potential of real-time monitoring of subglottal pressure during an individual's daily life for the prevention, assessment, and treatment of voice disorders.

Introducing a New Dosimeter for the Assessment and Monitoring of Vocal Risk Situations and Voice Disorders

PURPOSE

There are many physiological parameters recorded by devices that are becoming more affordable, precise and accurate. However, the lack of development in the recording of voice parameters from the physiological or medical point of view is striking, given that it is a fundamental tool for the work of many people and given the high incidence and prevalence of voice pathologies that affect people's communication. In this paper we perform a complete literature review on the dosimeters used in voice research and to present a prototype dosimeter with a pilot study to show its capabilities.

METHOD

We conducted a literature review using the keywords [MONITORING], [PHONATION], [ACCUMULATOR], [PORTABLE], [DOSIMETRY], [VOICE] searching in PubMed, Trip Database, HONcode, and SciELO search engines. From our review of dosimeter designs, we created our own prototype consisting of two main components: a Knowles Electronics BU-7135-0000 accelerometer mounted on a neck brace; and the ultra-low power MSP430FR5994 microcontroller. The selected sampling frequency was 2048 Hz. The device calculates the F0 every 250 ms and the amplitude and phonation activity every 31.25 ms. A pilot study was conducted using 2 subjects: one male during 11 days and one female during 14 days.

RESULTS

This work includes devices that have been created during the last 45 years as tools for the diagnosis and monitoring of the treatment of cases of vocal pathology and for the detection of phonatory patterns or risk situations for developing voice disorders or vocal pathologies. We also present recordings with our new device on the pattern of daily talk time, the fundamental frequency and the relative intensity of two subjects on different days.

CONCLUSIONS

Interesting work has been done in the development of voice dosimeters with different approaches. In our experience it is not possible to access them for research and they are not yet in clinical use. It is possible that a joint approach with voice and voice disorders professionals and engineers working closely together could take advantage of current technology to develop a fully portable, useful, and efficient system.

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.

The Effect of Superficial Hydration, With or Without Systemic Hydration, on Voice Quality in Future Female Professional Singers

OBJECTIVE

The aim of this study was to describe the effect of superficial hydration, with or without systemic hydration, on voice quality in future female professional singers by assessing acoustic and perceptual parameters of voice production as well as symptoms of vocal fatigue.

STUDY DESIGN

This is an experimental design study.

METHODS

A study was performed on a sample of 24 female voice majors to ascertain the effect of superficial hydration, with or without systemic hydration, on acoustic parameters and perception of vocal fatigue. The study replicated a prior study by van Wyk et al (2016) with some modifications; we looked at the effect of both systemic and superficial hydration independently and together on voice quality and vocal fatigue. Acoustic measurements including GRBASI, jitter, shimmer, F₀ MPT, frequency min and max, intensity min and max, and dysphonia severity index were measured along with perceived vocal fatigue using the Vocal Fatigue Index.

RESULTS

A statistically significant increase in MPT values were obtained when comparing pre- and post-test results of the hypo hydrated (P = 0.015) and superficial hydration condition (P = 0.004). A significant increase in frequency min (Hz) within the hypo hydrated condition was also observed (P = 0.019). A significant increase was observed in the intensity min (dB) (P = 0.010) and F₀ min (Hz) (P = 0.002) within the combined hydration condition. Also, when superficial hydration was applied, mean shimmer % (P = 0.016), MPT (sec) (P = 0.003) and dysphonia severity index (P = 0.020) scores increased significantly in a between-group, post-test comparison. A significant reduction in mean intensity max (dB) (P = 0.049) and intensity min (dB) (P = 0.018) was also observed.

CONCLUSIONS

This study demonstrates that the use of superficial hydration results in positive outcomes of perceptual parameters of voice quality and symptoms of vocal fatigue in future female professional singers. However, mixed results were observed regarding the acoustic parameters of voice. The superficial hydration data is compelling enough to warrant implementing in a vocal hygiene protocol for singers.

The Impact of Cumulative Vocal Demands on Vocal Performance of Student Clinicians in Speech-Language Pathology

Effects of cumulative vocal demands on voice performance of student clinicians majoring in speech-language pathology were observed at three distinct points over the period of an academic semester. Acoustic and aerodynamic voice parameters were monitored in controlled and natural settings; participants also provided subjective information related to their voice usage. Comparisons of voice parameters in student clinicians repeatedly measured throughout an extended period of time did not lead to statistically significant differences. Self-reported data revealed a satisfactory level of knowledge and awareness regarding voice concerns in this population. These outcomes suggested consistent voice stability in this group, over the cycle of an academic semester.

Accuracy of Self-Reported Estimates of Daily Voice Use in Adults With Normal and Disordered Voices

PURPOSE

Accurate estimation of daily patterns of vocal behavior is essential to understanding the role of voice use in voice disorders. Given that clinicians currently rely on patient self-report to assess daily vocal behaviors, this study sought to assess the accuracy with which adults with and without voice disorders can estimate their amount of daily voice use in terms of phonation time.

METHOD

Eighteen subjects (6 patients, 6 matched members of a control group without voice disorders, 6 low voice users) wore the accelerometer-based Ambulatory Phonation Monitor (APM; model 3200, KayPENTAX, Montvale, NJ) for at least 5 workdays. Subjects were instructed to provide hourly self-reports of time spent talking using a visual analog scale. Spearman correlation coefficients and errors between self-reported and APM-based estimates of phonation time revealed subject- and group-specific characteristics.

RESULTS

A majority of subjects exhibited a significant bias toward overestimating their phonation times, with an average absolute error of 113%. Correlation coefficients between self-reported and APM-based estimates of phonation time ranged from statistically nonsignificant to .91, reflecting large intersubject variability.

CONCLUSIONS

Subjects in all 3 groups were moderately accurate at estimating their hourly voice use, with a consistent bias toward overestimation. The results support the potential role that ambulatory monitoring could play in improving the clinical assessment of voice disorders.

Comparison of vocal loading parameters in kindergarten and elementary school teachers

PURPOSE Although a global picture exists of teachers' voice demands in general, few studies have compared specific groups of teachers to determine whether some are more at risk than others. This study compared the vocal loadings of kindergarten and elementary school teachers; professional and nonprofessional vocal load were determined for both groups. METHOD Twelve kindergarten and 20 elementary school female teachers without voice problems were monitored during 1 workweek using the Ambulatory Phonation Monitor. Vocal loading parameters analyzed were F0, SPL, time dose, distance dose, and cycle dose. RESULTS Comparisons between the groups showed significantly higher cycle dose and distance dose for kindergarten teachers than for elementary school teachers, in both professional and nonprofessional environments. Professional and nonprofessional voice use comparisons showed significant differences for all parameters, indicating that vocal load was higher in the professional environment for both groups. CONCLUSIONS The higher vocal doses measured in kindergarten teachers suggest that particular attention should be paid to this specific group of teachers. Although nonprofessional vocal load is lower than professional vocal load, it is important to take both into account because of their cumulative effects.

Subglottal Impedance-Based Inverse Filtering of Voiced Sounds Using Neck Surface Acceleration

A model-based inverse filtering scheme is proposed for an accurate, non-invasive estimation of the aerodynamic source of voiced sounds at the glottis. The approach, referred to as subglottal impedance-based inverse filtering (IBIF), takes as input the signal from a lightweight accelerometer placed on the skin over the extrathoracic trachea and yields estimates of glottal airflow and its time derivative, offering important advantages over traditional methods that deal with the supraglottal vocal tract. The proposed scheme is based on mechano-acoustic impedance representations from a physiologically-based transmission line model and a lumped skin surface representation. A subject-specific calibration protocol is used to account for individual adjustments of subglottal impedance parameters and mechanical properties of the skin. Preliminary results for sustained vowels with various voice qualities show that the subglottal IBIF scheme yields comparable estimates with respect to current aerodynamics-based methods of clinical vocal assessment. A mean absolute error of less than 10% was observed for two glottal airflow measures -maximum flow declination rate and amplitude of the modulation component- that have been associated with the pathophysiology of some common voice disorders caused by faulty and/or abusive patterns of vocal behavior (i.e., vocal hyperfunction). The proposed method further advances the ambulatory assessment of vocal function based on the neck acceleration signal, that previously have been limited to the estimation of phonation duration, loudness, and pitch. Subglottal IBIF is also suitable for other ambulatory applications in speech communication, in which further evaluation is underway.

A comparison of vocal demands with vocal performance among classroom student teachers

PURPOSE

This investigation compared voice performance of student teachers across an academic semester in order to examine the effect of increasing demands on their voice.

METHOD

A repeated measures design was applied to the data analysis: all participants were tested three separate times throughout the semester. The equipments used for monitoring vocal behavior were the Ambulatory Phonation Monitor (APM), the Computerized Speech Lab (CSL), and the Phonatory Aerodynamic System (PAS), which are computer-based systems for acoustic and aerodynamic assessment of voice. Additionally, participants completed surveys related to voice usage.

RESULTS

In this study, most voice parameters of student teachers measured in a natural setting and in a controlled environment indicated changes that revealed progressive instability and noise in the course of an academic semester. Additional comparisons demonstrated differences between voice usage in the school environment and voice produced in the voice lab. Self-reported information demonstrated overall reduced awareness regarding preventive methods for voice disorders.

CONCLUSIONS

Based on the results of this study, increased teaching-related voice demands associated with reduced awareness of voice production and preventive measures of voice disorders may have a detrimental impact on voice performance, leading to a risk of developing voice disorders.

LEARNING OUTCOMES

Participants will recognize the importance of clarifying and quantifying the relationship of vocal demands and voice performance among student teachers.