Regulation of Voice Communication by Sensory Dynamics

People speak more loudly in a noisy room or when momentarily deafened and more softly in a quiet room or when sidetone is artificially increased. The effort to compensate for these changes in the signal-to-noise ratio, or to match directly changes in the intensity of a model, typically falls about halfway short (in decibel units). This is probably because a speaker considers that he has doubled his own vocal level in half as many decibels as it takes to double the loudness of the signal or the noise. More concisely, the Lombard-reflex, sidetone-penalty and cross-modality matching functions have exponents of about one-half because the exponent of the loudness scale is half that of the autophonic scale of voice level. This amounts to saying that the speaker matches changes in signal or in noise to keep the signal-to-noise ratio nearly constant, but he is misled by the disparity in the sensory operating characteristics of speaking and listening.