F0 control in electrolarynx speech.

Abstract

Over half of laryngectomy patients use an electrolarynx (EL) to communicate, but current EL devices produce a mechanical sound quality mainly due to the lack of natural F0 variation. In order to improve the sound quality of EL speech, the present study aimed to develop and evaluate an automatic F0 control scheme, where F0 in EL speech is covaried based on modulations in the rms amplitude of the EL speech signal. Declarative sentences ending with vowels produced by two male laryngectomy patients before and after the laryngectomy were used in order to develop procedures for controlling F0. The linear regression coefficients between F0 and rms amplitude in the normal speech were first determined and applied to the amplitude variation in EL speech to compute the F0 contour for the EL sentences. An analysis-by-synthesis approach was employed to modify the F0 contour of the EL speech as computed. Perceptual evaluation showed that the addition of amplitude-based F0 modulation resulted in EL speech that was judged to be more natural sounding than EL speech having constant F0, supporting the idea of using a simple linear relationship between amplitude and frequency to compute an F0 contour. [Work supported by NIH Grant No. R01DC006449.]