Acoustic Shock

Acoustic Shock

Acoustic Shock is entirely distinct from conventional Noise Induced Hearing Loss (NIHL) which is generally caused by prolonged or repeated exposure over a significant period of time (usually years). It is often confused with Acoustic Trauma which is also a form of conventional hearing loss, usually produced by loud impulses, but without necessarily a "shock" value. Conventional NIHL is covered by the Control of Noise at Work Regulations.

Acoustic Shock is very different. The "shock" element is as important as the noise level of the incident and it is the unexpected nature of it that is largely responsible for the adverse effects. Cases often rely on a lot of other evidence as the sudden nature of the incident can rarely be replicated for analysis. 

Acoustic Shock is referred to almost exclusively as a call centre phenomenon through headsets, and often described as short duration, with a rapid attack/rise time (ie. sudden), usually high frequency and always unexpected. It is often referred to as “feedback”, mainly due to the shrieking nature of the sound, rather than the actual source. However, despite being primarily associated with the call centre headsets, there is no reason why the causes of Acoustic Shock should not occur in many other settings.

There is no consistent threshold of noise that can trigger Acoustic Shock, but evidence suggests levels of 82 to 120 dB at the eardrum. These are not particularly high levels of noise (the ear canal has an amplifying effect so, very roughly, 82 to 120 dB at the eardrum would be around 72 to 110 outside the ear). The point is the suddenness of the sound and the “shock” reaction it can produce.