IMAGINE waking up one day to find that the world has become louder. Sounds that once were tolerable 鈥� running water, footsteps, a ringing phone 鈥� are suddenly deafening. It鈥檚 as if someone has turned up the volume. You want to run and hide but it follows you everywhere.
鈥淭o a sufferer, even the sound of their own voice can be intolerable鈥�
This is the world experienced by sufferers of hyperacusis 鈥� literally, excessive sensitivity to normal sounds. It can range from an annoyance to a completely debilitating disorder. Sufferers don鈥檛 have better hearing than everyone else; rather, they perceive sounds to be much louder than they actually are. While an average person can tolerate anything up to 100 decibels, which corresponds to the sound of a car horn blasting in your ear, the maximum level someone with hyperacusis can tolerate is usually only 60 decibels, the level of normal conversation. An ordinary voice sounds more like gunshots. To a sufferer, even the sound of their own voice can be intolerable. There may be millions of people living with this condition.
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What causes hyperacusis? Nobody knows. It can be brought on by, among other things, head injuries, exposure to extremely loud sounds, Lyme disease and autism. It has also been linked with tinnitus, a disorder that causes people to hear phantom sounds, such as ringing or buzzing. The main question puzzling researchers is whether it鈥檚 the result of structural damage to the ear or flaws in the way the brain interprets sound signals. The disorder has not been well studied, partly because it is often misdiagnosed as a psychological problem. Sufferers tend to isolate themselves to avoid noise, be unable to hold down a job, avoid social interaction and suffer anxiety attacks 鈥� symptoms easily mistaken for a mental disorder.
Is there a cure? Not yet, though there are treatments. The most successful is a therapy using so-called 鈥減ink noise鈥� 鈥� a sound spectrum in which the amplitude decreases with increasing frequency, so low notes are louder than higher ones. It is a good model for everyday environmental sounds. If hyperacusis sufferers can gradually be desensitised to pink noise they will learn to better tolerate the sounds of the outside world. They can do this by listening to specially recorded pink noise CDs, or better still by wearing custom-fitted sound generators that transmit pink noise straight into the ear.
Some researchers suggest that hyperacusis is a thoroughly modern disorder partly caused by noise pollution from traffic, aircraft and even personal music players. This is speculative, though it鈥檚 true that the level of background noise generally considered acceptable has increased over time, especially in cities. The solution? Move to the country 鈥� or wear earplugs.
