The most common types of voice disorders are associated with hyperfunctional voice use in daily life. Although current clinical practice uses measures from brief laboratory recordings to assess vocal function, it is unclear how these relate to an individual's habitual voice use. The purpose of this study was to quantify the correlation and offset between voice features computed from laboratory and ambulatory recordings in speakers with and without vocal hyperfunction. Features derived from a neck-surface accelerometer included estimates of sound pressure level, fundamental frequency, cepstral peak prominence, and spectral tilt. Whereas some measures from laboratory recordings correlated significantly with those captured during daily life, only approximately 6-52% of the actual variance was accounted for. Thus, brief voice assessments are quite limited in the extent to which they can accurately characterize the daily voice use of speakers with and without vocal hyperfunction.

We investigate the connection between the autonomic nervous system and the voice in patients with vocal hyperfunction and healthy-control groups. We present a methodology and preliminary results of two multi-modal measurement streams that capture this relationship. Subjects were instrumented for daily, ambulatory collection of their voice and wrist-based electrodermal activity. Measures of vocal function (e.g., fundamental frequency) were computed, as well as measures of autonomic function (e.g., skin conductance response). Spearman correlation coefficients were calculated to measure the relationship between vocal and autonomic function over sliding windows throughout each observation day. We found preliminary evidence that patients with a subtype of vocal hyperfunction (non-phonotraumatic vocal hyperfunction) exhibit a coupling between the autonomic nervous system and the vocal system. Understanding how the autonomic nervous system interacts with the voice may provide new insights into the etiology/pathophysiology of vocal hyperfunction and improve prevention, diagnosis and treatment of these disorders.

Monitoring subglottal neck-surface acceleration has received renewed attention due to the ability of low-profile accelerometers to confidentially and noninvasively track properties related to normal and disordered voice characteristics and behavior. This study investigated the ability of subglottal neck-surface acceleration to yield vocal function measures traditionally derived from the acoustic voice signal and help guide the development of clinically functional accelerometer-based measures from a physiological perspective. Results are reported for 82 adult speakers with voice disorders and 52 adult speakers with normal voices who produced the sustained vowels /a/, /i/, and /u/ at a comfortable pitch and loudness during the simultaneous recording of radiated acoustic pressure and subglottal neck-surface acceleration. As expected, timing-related measures of jitter exhibited the strongest correlation between acoustic and neck-surface acceleration waveforms (r≤0.99), whereas amplitude-based measures of shimmer correlated less strongly (r≤0.74). Additionally, weaker correlations were exhibited by spectral measures of harmonics-to-noise ratio (r≤0.69) and tilt (r≤0.57), whereas the cepstral peak prominence correlated more strongly (r≤0.90). These empirical relationships provide evidence to support the use of accelerometers as effective complements to acoustic recordings in the assessment and monitoring of vocal function in the laboratory, clinic, and during an individual's daily activities.

Many common voice disorders are chronic or recurring conditions that are likely to result from inefficient and/or abusive patterns of vocal behavior, termed vocal hyperfunction. Thus an ongoing goal in clinical voice assessment is the long-term monitoring of noninvasively derived measures to track hyperfunction. This paper reports on a smartphone-based voice health monitor that records the high-bandwidth accelerometer signal from the neck skin above the collarbone. Data collection is under way from patients with vocal hyperfunction and matched-control subjects to create a dataset designed to identify the best set of diagnostic measures for hyperfunctional patterns of vocal behavior. Vocal status is tracked from neck acceleration using previously-developed vocal dose measures and novel model-based features of glottal airflow estimates. Clinically, the treatment of hyperfunctional disorders would be greatly enhanced by the ability to unobtrusively monitor and quantify detrimental behaviors and, ultimately, to provide real-time biofeedback that could facilitate healthier voice use.

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.

Voice use is considered to play a major role in the development of many voice disorders, and clinicians focus on evaluating and modifying how patients use their voices throughout the day. Some voice monitoring devices have used neck-mounted accelerometers to unobtrusively and confidentially track voice use–related measures, such as phonation time, fundamental frequency, and sound intensity. Guidelines for the clinical use of such monitoring devices have yet to be established. This is a preliminary investigation into establishing initial benchmarks for obtaining robust estimates of long-term average voice use that may be used to begin examining basic relationships between vocal loading and voice use–related pathology. As expected, adequate monitoring durations depend on the inherent variability of the parameter of interest, with much of the error decreased after 26 hours of monitoring. Investigations are currently under way to take advantage of a smartphone-based voice monitoring system that is designed to enhance device wearability and enable the derivation of new clinically relevant measures. Index Terms: ambulatory voice monitoring, voice use, voice disorders, accelerometer 1.

For many individuals who lose their voices due to laryngeal cancer or trauma, the only option for speech is to use an electrolarynx (EL), which is a battery-powered vibrator that is held to the throat. Current devices produce speech that is very machine-like in sound, with low levels of loudness and intelligibility, that also draws undesired attention to the user. A project at Draper Laboratory, the Mass. Eye and Ear Infirmary and MIT aims to develop a much improved EL called the electrolarynx communication system (ELCS), which is a DSP-based device consisting of sound source, control, and speech enhancement subsystems or modules. This paper introduces the ELCS and discusses developments to date in the sound source module. Specific topics include the design of a new linear EL transducer and investigations into glottal waveform synthesis which should result in a much more natural speech output.

This paper demonstrates that linear discriminant analysis using aerodynamic and acoustic features is effective in discriminating speakers with vocal-fold nodules from normal speakers. Simultaneous aerodynamic and acoustic measurements of vocal function were taken of 14 women with bilateral vocal-fold nodules and 12 women with normal voice production. Features were extracted from the glottal airflow waveform and peaks in the acoustic spectrum for the vowel /ae/. Results show that the subglottal pressure, air flow, and open quotient are increased in the nodules group. Estimated first-formant bandwidths are increased, but result in minimal change in the first-formant amplitudes. There is no appreciable decrease in high frequency energy. Speakers with nodules may be compensating for the nodules by increasing the subglottal pressure, resulting in relatively good acoustics but increased air flows. The two best features for discrimination are open quotient and subglottal pressure.