What's that, anyway?
Noise is any type of sound that can disturb, annoy, or impair a person's health. World Health Organisation, 2000
How loud a sound is perceived depends on the following factors:
Depending on the listener and his perception of sounds, the same sound sources are perceived differently loud and/or annoying. The transmission of the stimuli depends on the modulation of the sound.
Lärm ist das Geräusch der anderen.
Noise is the sound of others. Kurt Tucholsky
Sound becomes noise if it causes disturbances, nuisances, impairments or damage.
Strong noise exposure can have health consequences. Noise-induced hearing loss, which is a direct damage to the hearing (= aural effect), should be mentioned here as a proven fact. Long-term exposure to average sound pressure levels of more than 80 dB(A) (related to a 40 hour week) leads to an increase in the risk of damage to the inner ear in the form of irreversible hearing loss. Bavarian State Office for Health and Food Safety