Acoustic shock is the set of symptoms a person may experience after hearing an unexpected, loud

sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' b ...

. The loud sound, called an acoustic incident, can be caused by feedback

oscillation Oscillation is the repetitive or periodic variation, typically in time, of some measure about a central value (often a point of equilibrium) or between two or more different states. Familiar examples of oscillation include a swinging pendulum ...

fax Fax (short for facsimile), sometimes called telecopying or telefax (the latter short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer o ...

tones, or signalling tones. Telemarketers and call centre employees are thought to be most at risk.ITU-T Recommendation p.10 (12/98): Vocabulary of terms on telephone transmission quality and telephone sets, Geneva, 1998.

Reported symptoms

During the exposure, most people experience

discomfort Comfort (or being comfortable'')'' is a sense of physical or psychological ease, often characterized as a lack of hardship. Persons who are lacking in comfort are uncomfortable, or experiencing discomfort. A degree of psychological comfort c ...

and pain. After the exposure, some people might report

shock Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emergen ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

and

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...

or depression.Acoustic Shock
Headache, fatigue, hypersensitivity to loud noise and

tinnitus Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...

may continue for days, weeks or indefinitely.Appendix 7 – Acoustic shock
/ref> It has not been established how such unrelated symptoms might be caused by an acoustic exposure, or whether such symptoms are even a direct result of exposure. There is literature that suggests acoustic shock is not a pathological entity but predominantly psychogenic.

Physiological mechanisms

It has been suggested that the tensor tympani is involved in causing the disorder (see

tonic tensor tympani syndrome Tonic tensor tympani syndrome is a disease of the tensor tympani muscle, described by Klochoff et al in 1971.Klockhoff I. Impedance fluctuation and a ''Tensor Tympani Syndrome''. In: Proceedings of the 4th International Symposium on Acoustic Measur ...

). In France, researchers report the study of a case of acoustic shock in a scientific publication. They suggest that these symptoms may result from a loop involving the middle ear muscles, peripheral inflammatory processes, activation and sensitization of the trigeminal nerve, the autonomic nervous system, and central feedbacks.

Prevention

There are many methods of attempting to reduce the risk of AS. Several devices attempt to remove potentially harmful sound signals by digital signal processing. None has yet been shown to be fully effective. Devices which solely limit noise levels to about 85 dB have been shown in field trials to be ineffective (data from these trials has not been released into the public domain). Limiting background noise and office stress may also reduce the chance of an acoustic shock. Proper use of the headset and preventing mobile phones from being used in call centers reduces the chance of feedback.

Legal action

84 BT employees with depression, headaches and other health problems demanded compensation for injury sustained from acoustic shock at work. BT has already paid £90,000 to one worker who had tinnitus. In March 2018, a musician won a claim for damages against the British

Royal Opera House The Royal Opera House (ROH) is an opera house and major performing arts venue in Covent Garden, central London. The large building is often referred to as simply Covent Garden, after a previous use of the site. It is the home of The Royal Ope ...

for acoustic shock caused by excessive noise during orchestral rehearsals.

References

External links

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