Sound and noise

Extra-auditory effects of noise on the body

The extra-auditory effects of noise are the effects resulting from exposure to acoustic stresses, but that do not concern the ears, i.e. noise that does not harm the hearing.

Noise, even at relatively low intensities, can act as a 'stressor' owing to the annoyance or disruption it causes and can therefore harm general health. The negative impact of noise depends on how the individual perceives it. The objectifiable effects of exposure to noise are vasoconstriction of the peripheral blood vessels, slow, deep breathing, changes in the electrical resistance of the skin and a slight modification of muscle tone, sleep problems, and increased blood pressure and heart rate.

Harmful effects on hearing

A distinction is made between:

• Acute acoustic trauma: hearing problems appear following short but violent acoustic events (explosions, detonations)
• Chronic acoustic trauma: the hearing problems are caused by prolonged acoustic trauma (over years)

If the injuries are so significant that they prevent the understanding of everyday language, this is called noise-induced deafness.

Permanent exposure to noise, as is often the case in the world of work, first causes reversible hearing problems (TTS = Temporary Threshold Shift). The recovery time depends on the extent of the TTS. If subsequent exposure to noise affects a hearing organ that has not fully recovered, the result is a Permanent Threshold Shift (PTS).

For noise intensities less than 85 dB(A), there is no risk of hearing problems, but as noise intensity increases, the greater the risk of hearing problems.