Quantitative detection of substitute voice generator during phonation in patients undergoing laryngectomy

OBJECTIVE: To evaluate the vibration pattern of the substitute voice generator of patients who have undergone laryngectomy. For automatic quantification of the oscillations of the pharyngoesophageal (PE) segments, image processing of digital high-speed video sequences is applied. DESIGN: Physiologic analysis. SETTING: An acute care hospital. PATIENTS: Endoscopic recordings were taken of 10 men who underwent laryngectomy (mean +/- SD age, 61.5 +/- 5.2 years) during sustained phonation of a vowel using a 90 degree endoscope coupled to a high-speed camera. MAIN OUTCOME MEASURES: An image-processing algorithm was developed to automatically define the pseudoglottis in each recording and track its movements. RESULTS: The clinical assessment of the high-speed technique for the endoscopic examination of the substitute voice generator yields the following results. The forms and oscillation characteristics of the pseudoglottides varied considerably: 3 pseudoglottides were circular, 6 were split shaped, and 1 was triangle shaped. A quasi-periodic opening and closing were observed and automatically detected by the described algorithm in each recording independently from quality of the recording and from morphologic and oscillation characteristics of the PE segment. The frequencies of the extracted oscillations of the pseudoglottides correspond to the structure of the acoustic signals. CONCLUSIONS: Automatic image processing of PE segments derived from high-speed endoscopic recordings enables the detection and quantification of the substitute voice generator's oscillations in high temporal resolution. These data directly prove that the detected pseudoglottis is the source of the substitute voice. Close relations between substitute voice and functional properties of the PE segment exist. In the future, these data will be interpreted by applying biomechanical models of the PE segment. Presumably, results may help to optimize surgical and adaptive procedures for specific substitute voice restoration.