Adaptive plasticity of loudness induced by chronic attenuation and enhancement of the acoustic background

Strategies for treating hyperacusis, an anomolous condition of loudness perception, paradoxically seek either to minimize or enhance listeners' sound exposures.. We show that these reciprocal treatment approaches, implemented with similar amounts of background sound attenuation and enhancement, produce diametrically opposite perceptual effects in normal listeners. Specifically, we show after continuous, 2-week earplugging and low-level noise treatments that listeners become more and less sensitive, respectively, to the loudness of sounds. This simple demonstration of adaptive plasticity is consistent with modification of a theoretical gain control process, which is the basis for desensitizing sound therapies used in treating hyperacusis and related sound tolerance problems. (C) 2003 Acoustical Society of America.