TEMPERATURE DISTRIBUTION IN EXPIRATORY SPEAKING FLOW, AND EARLY DETECTION OF VOCAL FOLD PATHOLOGY

This paper describes an application of heat transfer fundamentals to t he development and testing of an instrument with potential use for spe ech production analysis. The method exploits an assumed difference bet ween the air flow patterns of individuals with healthy and breathy voi ces: during breathy speech production, the glottis does not close comp letely, and the leakage of warm air through the glottis increases the extent of the temperature field outside the oral cavity. The proposed instrument is a pipe through which the tested individual breathes out while producing a sustained vowel. The pipe wall temperature is mainta ined uniform at a level considerably lower than the body temperature. The temperature gradient along the pipe centreline is measured and rel ated to the average air velocity through the glottis. The measurements compare favourably with numerical results for the temperature field i nside the instrument. These findings therefore suggest that the temper ature distribution outside the oral cavity could be useful in understa nding changes in air flow patterns through the vocal folds. The centre line temperature chart to be used in conjunction with the instrument i s reported in dimensionless terms.