Noise is a complex sound produced by various vibrations, that are often absorbed and are not harmonic.

Sound is an auditory sensation (involving physiological and psychological phenomena) generated by a sound wave (physical phenomenon).

The propagation speed or velocity of sound depends on its nature, as well as its temperature and pressure.

In vacuum, sound does not travel because there is no matter to carry the waves. Sound insulation uses this property.

Sound is different in a church, a movie theater, concert, in an empty room and in a furnished room...this is due to reverberation. It allows us to aurally identify the type of space in which we find ourselves. It gives momentum to the sound. Without reverberation, sound would be dry and flat.

Three million employees reported being exposed to noise above 85dB (A) in France in 2003 (SUMER Report).

Sound has multiple effects on the body: auditive problems such as tinnitus or hearing loss, and non-auditive problems such as stress, fatigue and even cardio-vascular diseases.

Reduction in alertness and attention span, difficulty in concentration; these effects of noise exposure increase the risk of accidents in the workplace

According to DARES, difficult working conditions are often accompanied by an increased risk of accident. This mainly occurs in the case of noise: 8.6% of employees exposed to harmful noise (+ 85dB (A), + 20 hours/week) experienced lost-time injuries.

A loud and constant noise can cause loss of alertness or prevent the perception of danger (Campo, 2005).

Noise increases the risk of lost-time injury by 24%.