Hyperacusis is a medical term used to describe any abnormal discomfort caused by sounds that are tolerable to listeners with ordinary hearing. It is often viewed as a phenomenon, because it is a subjective experience it cannot be measured directly and is, consequently, very difficult to study and to diagnose.
Hyperacusis should be distinguished from another phenomenon known as recruitment. Recruitment is commonly associated with hearing loss caused by damage to the sensory cells of the inner ear, where although weak sounds cannot be heard but louder sounds are perceived at their normal level, and may cause the listener discomfort and pain.
Many people who experience Hyperacusis have no detectable hearing loss, (the ears are working normally) although it can be linked with other hearing problems such as tinnitus (buzzing or ringing in the ears) and Ménière’s Disease (vertigo combined with a hearing loss and tinnitus). Others do have a hearing loss and the fitting of hearing aids needs careful consideration. It is believed that in childhood, 6% of the population may suffer oversensitivity to noise, with the prevalence in adults slightly higher around 8%.
Hyperacusis may occur following trauma to the head or after exposure to loud noise but, for many people, the onset is sudden and unexplained. It may occur independently of any other identifiable conditions, but Hyperacusis is a recognised symptom of several conditions. Aside from tinnitus and Ménière’s Disease, Hyperacusis is sometimes associated with post-traumatic stress disorder, migraine, some types of depression, vitamin B6 deficiency and post-viral fatigue syndrome (or ME).
Volume is not necessarily the problem, with Hyperacusis it may be the frequency (pitch) of the sound rather than its volume that causes distress. Electrical and machine noises seem to be amongst the sounds least well tolerated but it is not clear why individual sufferers are disturbed by some sounds while other, often louder sounds, do not cause problems.
Adult sufferers may avoid noisy situations and may become socially isolated and for some their condition worsens at night causing extreme sleep disturbance. This in turn has an impact on family and work life. For children background noise can make concentration at school very difficult and result poor achievement. Although children may find that the problem lessens over time, this does not seem to be the case in adults. In fact where sounds have become associated with pain or discomfort, fear or anxiety about these sounds may become established, turning acute Hyperacusis into a chronic, debilitating condition.
There are a number of treatment strategies for Hyperacusis, but most will involve learning what kind of noise(s) trigger the pain/anxiety, then trying to desensitise the individual to that sound. Noise generators play an important part in this process. These electronic devices look like hearing aids but actually produce a steady, gentle noise, they have a volume control, allowing the noise level to be adjusted. The aim of using noise generators is to reduce the sensitivity of the ear.
Noise generators are worn behind the ear in a similar way to a hearing aid. The sound is fed into the ears through an ear mould which is specifically designed not to block the ear canal, allowing background noise to be heard normally. The ear mould and device must be comfortable and secure so that it is possible to build up the number of daily hours of use over time in comfort. As hearing sensitivity usually occurs in both ears, both ears will usually be fitted.
Most adults using a noise generator report that after using the generators over a period of use of around one year to eighteen months, their hearing sensitivity becomes much more normal and therefore the need for the generators lessons.
Where the individual also has a hearing loss and a need for a hearing aid/s, this must be done without overloading the ear with amplified sound. Most hearing aids systems now have some form of compression, which effectively stops any loud sounds entering the hearing aid from being over-amplified and causing discomfort.