This article is from the Tinnitus FAQ, by email@example.com (Mark Bixby) with numerous contributions by others.
Although there may be as many as 1% of the population who are sound
sensitive, hyperacusis sufferers go well beyond the definition of sound
sensitive and often cannot tolerate their surroundings or even people's
voices. Because the media has not publicized this disorder it is hard to
get a handle on how rare hyperacusis is, however, it may be as little as
one in every 50,000 people. That is extremely rare!