The MGH Voice Center (PI: Mehta) has been awarded one of the first Early Career Research R21 grants (formerly R03 grants) from the NIH National Institute on Deafness and Other Communication Disorders. The three-year project: Non-invasive estimation of subglottal pressure during natural speech to improve clinical voice assessment.
Voice disorders affect approximately 30% of the adult population in the United States at some point in their lives and up to 7.6% at any given point in time, with far-reaching social, professional, and personal consequences. Subglottal air pressure (Ps) plays a major role in voice production and is a primary factor in controlling voice onset, offset, and intensity, and also contributes to variation in fundamental frequency. Ps is a central component of vocal efficiency measures and is associated with aspects of perceived vocal effort. In terms of clinical voice assessment, Ps alone, and in combination with other vocal parameters, has been shown to differentiate between normal and disordered voice production, including providing insights into changes in vocal function associated with treating voice disorders. Unfortunately, current use of Ps for clinical and research purposes is significantly limited because estimating Ps involves invasive, cumbersome procedures or non-natural speech tasks.
This project seeks to develop a non-invasive method for estimating Ps during natural speech production that is based on sensing the acceleration of the neck skin surface during phonation. The method uses an unobtrusive miniature accelerometer (ACC) attached to the anterior base of the neck, an approach that our group has helped pioneer and continues to develop for ambulatory voice monitoring. Our preliminary results show that the amplitude of the neck-surface ACC signal can provide robust estimates of Ps during normal modal voice production across multiple pitch and vowel contexts. The proposed work pursues the next critical goals to (a) quantify the impact of non-modal phonation and vocal pathologies on amplitude-based ACC estimates of Ps and (b) compensate for this impact by incorporating additional ACC-based measures of glottal function. To begin systematically determining the impact of different glottal conditions on ACC-based estimates of Ps in a controlled manner, vocally normal individuals will produce voice samples using different voice qualities to mimic dysphonia (normal, breathy, pressed, and rough). Clinical data will be obtained from patients with voice disorders representing a spectrum of pathological glottal conditions: vocal fold nodules and/or polyps, muscle tension dysphonia, and unilateral vocal fold paralysis/paresis.
A non-invasive, inexpensive, and accurate method for estimating Ps during natural speech has the potential to significantly improve the study and clinical assessment of voice, particularly for application to ambulatory monitoring and biofeedback as individuals go about their usual activities at home, work, and social settings.