How everyday sounds can drive people crazy
Loud chewing, soup slurping, finger tapping, knuckle cracking, whistling… these sounds may be a mild annoyance to most people, but for some, everyday noises can trigger irrational responses of anger or fear.
This condition is known as misophonia – “hatred of sound” – or selective sound sensitivity syndrome. Although it has only recently been recognised as an affliction, it can cause sufferers great distress. The sound of somebody smacking their lips while eating can make someone with misophonia feel uncontrollably angry or anxious. In extreme cases, they may fly into a rage, or act on their strong desire to make the noise stop. They may also experience physical effects such as pressure in the chest, tensing muscles and an elevated heart rate – similar to the fight-or-flight response.
Misophonia has not been particularly well studied, but doctors think it could be related to how the brain processes sound. It is possible that sufferers have unusually strong connections in their brains between the auditory system, which deals with sound, and the limbic system, which controls emotion.
In extreme cases, they may fly into a rage, or act on their strong desire to make the noise stop…
Sound waves make tiny bones in our ears vibrate, which are transformed into electrical signals by the cochlea, which are then transmitted along the auditory nerve to the thalamus in the brain. From the thalamus, the signal can be transmitted via two different routes to the amygdala – the part of the brain that processes primal emotions such as fear and pleasure.
One thalamus-amygdala route is direct for a fast response, so if you hear a sudden loud noise, you jump automatically. The longer route goes via the medial prefrontal cortex, which takes more time but analyses the situation for an appropriate emotional response. Some experts think that when misophonia sufferers hear trigger noises, the longer route is not involved so the response is irrational and intense.
Research conducted by the University of Amsterdam found that the most common trigger sounds were eating sounds (including chewing, lip smacking and swallowing), breathing sounds (such as yawning, sneezing and sniffing) and hand sounds (typing, pen-clicking and knuckle cracking).
When misophonia sufferers hear trigger noises, the response is irrational and intense…
A misophonia study by the University of California at San Diego used electrodes to measure the electrical conductance of sufferers’ skin (a commonly used measure of physiological response, as the skin becomes more conductive as you sweat) while they were played certain sounds. When listening to soothing sounds (like rainfall) they did not react, but their skin conductance shot up when played the sound of gum chewing.
Another study found that misophonia was surprisingly common, with as many as 20% of those surveyed reporting significant symptoms of the condition. Many of those questioned admitted to having to avoid social situations that they knew could trigger outbursts, such as eating in restaurants or going to the cinema.
Until more is known about what causes such irrational reactions to sound, it is quite difficult to treat. While avoidance is a common coping mechanism, this can negatively impact people’s daily lives. Some research has shown that cognitive behavioural therapy can help misophonia sufferers change how they react, distracting them from the trigger and reducing the anger response.
Discover more amazing science in the latest issue of How It Works. It’s available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, make sure you subscribe today!