Vocal effort is a quantity varied by speakers when adjusting to an increase or decrease in the communication distance.
Vocal effort is a subjective physiological quantity, and is mainly dependent on subglottal pressure, vocal fold tension, and jaw opening.
To measure vocal effort, listeners are asked to rate the distance between the speaker and the addressee.
Several professional occupations requiring heavy vocal use, such as sport and fitness instructor, have been associated with an increase in developing vocal pathologies [2]
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