Abnormal hearing sensitivity. Some times described as “noise intolerance.” If you have hyperacusis, you now perceive sound of normal volume as much too loud. In fact, your may perceive them as being painfully loud. Hyperacusis can be caused by exposure to loud sounds, or as a result of taking certain drugs. Hyperacusis can be defined as an abnormally strong reaction to sound occurring within the auditory pathways. At the behavioral level, it is manifested by a person experiencing physical discomfort as a result of exposure to sound (quiet, medium or loud). The same sound would not evoke a similar reaction in an average listener. The strength of the reaction is controlled by the physical characteristics of the sound, e.g., its spectrum and intensity.