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.
Department of Electronic Engineering, Universidad Técnica Federico Santa Maíia, Valparaíso, Chile.
Matías
M
Zañartu
Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, 47901 USA.
Julio C
JC
Ho
School of Engineering and Applied Sciences, Harvard University and the Center for Laryngeal Surgery & Voice Rehabilitation, Massachusetts General Hospital, Boston MA 02114 USA.
Daryush D
DD
Mehta
Center for Laryngeal Surgery & Voice Rehabilitation at Massachusetts General Hospital, Harvard Medical School, and Harvard-MIT Division of Health Sciences and Technology, Boston, Massachusetts 02114.
Robert E
RE
Hillman
Weldon School of Biomedical Engineering and the School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47901 USA.
George R
GR
Wodicka
Inverse filtering; accelerometer; ambulatory monitoring; glottal airflow; glottal source; neck vibration; vocal folds; voice production