Acoustic analysis of voice in patients treated by reconstructive subtotal laryngectomy. Evaluation and critical review.

Abstract

Aim of this investigation was to analyse the voice in a group of 20 patients submitted to supracricoid partial laryngectomy (cricohyoidopexy, sparing two arytenoids) by the Multi Dimensional Voice Programme acoustic analysis system. Results revealed the following sound characteristics: high rate of noise, lack of periodic component of the signal, high rate of segments with no sound signal, vocal segments with marked air-turbulent flow, variation amplitude and frequency coefficients doubled compared to normal values, average fundamental frequency, if present, extremely variable and unsteady. These results show that the phonatory ability of the residual larynx, due to the altered anatomo-physiology of the structure after surgery, has to be completely re-estimated. In fact, the residual larynx determines a definitely reduced periodic acoustic signal, rich in noise and which can not be modulated. Good phonatory results of this treatment are basically due to preservation of a still understandable (but not perfect!) speech which, by ensuring the subjects' speech ability, overcomes and has little influence on the really poor quality of the vocal signal in these patients. However, the patient obtains a "new voice" as far as concerns acoustic features and this is very important for communication and social life. Moreover, the possibility of objectively estimating acoustic vocal function ability allows monitoring of the trend and results of possible speech therapy and/or phonosurgical rehabilitation treatment which should start from new anatomical and physiological bases, as well as from the new physical acoustic mechanism of signal production.