A pilot study on the evaluation of normal phonating function based on high-density sEMG topographic maps

Phonation is controlled by complex synergism of muscles over the front neck region. Proper evaluation of the muscular activities in this region would not only help to estimate phonation function, but may also provide characteristics to diagnose dysphonia. While surface electromyography (sEMG) technique has been used to study the physiological aspects of phonation in previous studies, it remains unclear if the phonating function could be dynamically characterized by the sEMG signals of the neck muscles associated with phonation. In this study, almost 80 channels of high-density (HD) sEMG signals were acquired from four healthy subjects when the vowel /a/ was phonated across different pitches by them. The root mean square (RMS) of the HD sEMG signals was computed within a series of segmented analysis windows and used to construct dynamic sEMG topographic maps. And the RMS maps represented the energy distribution of the front neck muscles, which would provide both the temporal and spatial information in accordance with the physiological and biomechanical principles of phonation. Our pilot results from the sEMG topographic maps across different pitch levels showed that the muscular activities consistently increased with the enhancement of the pitch levels. This pilot study suggests that HD sEMG might be a potential tool to visualize the distribution of the muscular activities and observe the coordination of muscular contractions during phonation. Also, it might pave way for proper screening and diagnosis of dysphonia as well as its associated pathologies.