Study of vocal fold vibration using M-mode ultrasound: a proof of concept

Ultrasound has recently been suggested as an alternative to laryngoscopy for checking vocal fold movement after neck surgery. We propose to use M-mode ultrasound (MUS) to study vocal fold vibration in left and right hemilarynges. MUS is acquired along a 1D line in each hemilarynx for about 5 seconds during vowel phonation. Post-processing estimates spatio-temporal maps of fundamental and second harmonic frequencies. To validate our method, 108 recordings (MUS and voice) from 12 healthy subjects were acquired. We compared the fundamental frequency obtained by MUS with that from voice analysis. The median fundamental frequency was estimated by MUS with high accuracy (y=0.997x+0.293, r=0.999). In our current trial, estimated frequencies are limited to 250 Hz. In future work, frequency will be increased to 1 kHz to avoid aliasing at high pitch, and MUS will be tested on patients with vocal pathologies.