The range of sound we can hear is phenomenal; some people can literally hear a pin drop and yet most can still tolerate loud sounds such as heavy machinery.
Levels of loudness that cause discomfort differs from person to person and can also be affected by a person’s mood, for example we may be less tolerant of loud sounds if we are stressed.There are a number of different types of sound sensitivity:
- Hyperacusis is an unusually low tolerance to ordinary environmental sounds, which are tolerable to listeners with normal hearing. There are estimates that between 40-86% of people who report this also have tinnitus and most sufferers present with no obvious hearing loss.
- Phonophobia is the fear of sound, often relating to more specific sounds which often have emotional associations.
- Misophonia is the dislike of sound and again there may be a strong emotional association.
- Recruitment is a large increase in the sensation of loudness with only a slight increase in the actual intensity of a sound. Even though quiet sounds cannot be heard due to the presence of hearing loss, louder sounds may quickly become uncomfortable to the listener as they increase in volume. Recruitment is commonly associated with a sensorineural hearing loss and does not vary with emotions.
Sound sensitivity is a clinical enigma, as there is not a test which can diagnose it and as such it is frequently solely based on what the person describes.
Often the person does not have a universal dislike for all sounds but finds specific sounds uncomfortable. Typical examples are screaming children, mechanical noises and traffic noise; often it is the tone of the sound which is distressing rather than the volume of the sound.
What are the causes of sound sensitivity?
Research is unclear as to the exact mechanism and causes but possible suggestions are: an increase in a chemical in the brain that helps prioritise sound, following a head injury or exposure to loud noise. For many people however there is no obvious cause. A number of disorders listed below have also been linked as possible causes for hyperacusis symptoms:
- Bell’s Palsy
- Ramsay-Hunt Syndrome
- Perilymph fistula
- Autism (40% of sufferers describe hyperacusis)
- Post-Traumatic Stress Disorder
- Lyme disease
- Williams Syndrome (90% of sufferers describe hyperacusis)
- Multiple Sclerosis
How do you manage noise sensitivity?
Management works around finding strategies that benefit the person with hyperacusis. This may involve investigating the types of noises which trigger a reaction – understanding the anxiety this causes is central to all treatment.
Most patients will naturally withdraw from any situation where troublesome noises occur and can find themselves socially isolated, sometimes even wearing ear protection to reduce the intensity of noises. Long term use of hearing protection has the adverse effect of increasing the issue; living in a quiet bubble only accentuates the actual loudness of any noise when the listener moves outside of this environment.
The main focus of treatment is through desensitisation to general sounds and in the long term, the specific sounds linked to the sensitivity. This can be achieved through the use of a device called a white noise generator, a device that looks like a hearing aids and produces a constant ‘shhhh-ing’ sound over a range of volume levels.
The aim of wearing a white noise generator is to improve a person’s ability to tolerate normal sounds. Through using the generators over the course of 1-2 years, many people describing sound sensitivity report a dramatic improvement over this time. Alongside desensitisation should be support around the anxiety to sound exposure, ensuring a full and holistic approach is provided.
Below is an illustration of the fear and avoidance model to sound. The model shows the links with this behaviour and hyperacusis and this should be the basis for counselling with each patient.