Acoustic variability in electrolaryngeal speech

Abstract

The electrolarynx (EL) is a hand-held electronic device that provides individuals with a means of communicating verbally postlaryngectomy. The EL produces a vibratory sound source that can be transmitted through the neck, where it excites vocal tract resonances generating speech. While some users attain a high level of intelligibility, the sound is unnatural due to numerous acoustic defects. In this study users of two EL devices were compared: the Servox emits a constant F0; the TruTone’s F0 can be varied by the user. The 10 users studied (5 Servox, 5 TruTone) used their EL for at least 24 months and were judged to be proficient. Though a previous study [Watson and Schlauch, Am. J. Speech Lang. Pathol., 18(2) (2009)] showed that intelligibility increased for a user with variable F0, TruTone use was not correlated with greater intelligibility in this study, perhaps because these TruTone users did not vary F0 much (F0 range was 3 to 20 Hz for a corpus of Harvard sentences). Detailed acoustic analyses of EL speech were considered along with other factors such as age and duration of EL experience. Results suggest directions for refinement of EL devices and training protocols for both types of EL users.