Types of noise
To determine the effects of noise, it is also important to know how long a person is exposed to noise and how high the sound pressure is. A distinction is made between continuous noise – for example from machines such as pumps or fans – and so-called intermittent noise – such as an aircraft take-off or the ringing of the alarm clock. Very short sounds such as gunshots or explosions are called impulse noise.
Noise as a permanent stress
Based on the results of various scientific studies, it is a concern that continuous exposure above about 65 dB(A) a day can lead to an increased health risk. Evidence has been found of changes in metabolism and hormone balance, changes in brain wave activity, but also poor sleep and other stress symptoms. In the long term, this can lead to high blood pressure and heart attacks.
Damage caused by noise
Above a level of 85 dB, the hearing is damaged beyond the general health effect. In the case of short noise effects, such as hammer blows, firecrackers or listening to very loud music for a short time, there is only a temporary shift in the hearing threshold. The ear recovers from this after a period of rest.
However, if a person is exposed to noise above 85 dB over a longer period of time, hearing loss is likely to develop. Long-term exposure to machine noise, very loud music or bangs above 120 dB(A) permanently damages the very fine hairs (cilia) of the hair cells in the inner ear and causes a shift in the hearing threshold, which manifests itself as hearing loss. Occupational hearing loss is currently the number one occupational disease in Germany.