Relationship between vocal doses and voice disorders on primary school teachers

A growing number of teachers is affected by vocal effort, that is a physiological magnitude that accounts for the changes in voice production due to some factors like distance from the listener, noise and physical environment, while vocal load is the amount of voicing performed by speakers over time. A sustained vocal effort combined with a prolonged vocal load, is assumed to result in increased instances of voice disorders. The effects of voice disorders range from a mild disturbance of voice quality to complete loss of the normal speech functions. In order to investigate the vocal load on teachers some "vocal doses" related to long-time phonation have been proposed by Titze et al. (2003). The doses are obtained from the phonation time, the fundamental frequency and the sound pressure level recorded close to the speaker's mouth. The aim of the study was to investigate vocal doses and parameters in a sample of 29 primary school teachers during two or three working days and compare these objective data with self-reported disturbances, objective laryngeal findings and clinician rating evaluation of voice. The Ambulatory Phonation Monitor (APM 3200) by KayPentax®, is a portable device that was used for the analyses. It was worn by the volunteers over two or three working days.