Deafness is the second occupational disease and 750 cases are reported each year. Therefore , the level of noise exposure of employees must not exceed 85 dB (A ) Article R4431-2 of the Labour Code the risk of harm to the health of workers.
In France , a quarter of workers in the industry is facing so prolonged exposure to noise exceeding the regulatory limit.
Industrial processes emit noise. It is possible to isolate the noise sources with specific insulation . When this is not possible, and that employees are faced with these noisy environments , it is advised to use appropriate hearing protection. To determine the appropriate acoustic insulation , whether for machines or for human ears , it is essential to carry out a detailed analysis of the spectrum of noise by breaking it in octave bands .
To do this , you must perform a noise analysis by decomposing octave band , that is to say, a spectral analysis of the noise in order to obtain the equivalent noise level octave band Leq / octave. For a more detailed analysis , you can specify the measurement by decomposing the noise spectrum in 1 /3 octave Thus, it is possible to choose earplugs reducing the noise bands most impactful octaves ( Industrial machinery by example) and to maintain communication ( different octave band ) between employees for example.
When the exposure level exceeds 90 dBA , the worker has the obligation to wear protective . To the sounds of very short duration ( drop plate , blasting ... ) called pulsed sounds , the provision of protective is requested from 135 dB and the mandatory use above 140 dB.
For measuring a pulse sound, you should use the time weighting Impulse (I). You can use the "peak " function of the meter to quantify the noise exposure peak noise concerned. This function is used for loud noise is applied to the result weighting C , the peak level is called Lpk (C).