Speech Rehabilitation Methods for Laryngectomised Patients

Abstract

Rehabilitation of the ability to speak in a natural sounding voice, for patients who suffer larynx and voice box deficiencies, has long been a dream for both patients and researchers working in this field. Removal of, or damage to, the voice box in a surgical operation such as laryngectomy, affects the pitch generation mechanism of the human voice production system. Post-laryngectomised patients thus exhibit hoarse, whisper like and sometimes less intelligible speech – it is obviously different to fully phonated speech, and may lack many of the distinctive characteristics of the patients normal voice. However these patients often retain the ability to whisper in a similar way to normal speakers. This chapter firstly discusses how the laryngectomy affects speech before briefly reviewing the three common methods of speech rehabilitation in such patients. It then presents, as a fourth method, a engineering approach to providing laryngectomy patients the capacity to speak with a more natural sounding voice. As a side effect, this allows them to conveniently use a mobile phone for communications. The approach is non-invasive and uses only auditory information, performing analysis, formant insertion, spectral enhancements and formant smoothing within the reconstruction process. In effect, natural sounding speech is obtained from spoken whispers, without recourse to surgery. The method builds upon our previously published works of using an analysis-by-synthesis approach for voice reconstruction.