I. 2. Classification of noise pollutionAccording to the physical properties of sound can be divided into the following categories: noise• Stable noise: sound intensity change Level no more than 5 dBA during noise.• Noise Level: the sound intensity changes over time in excess of 5dBA. There are 3 places type noise is not stable:-Noise and vibrations-Noise intermittently-Impulse noise PayamAccording to the distribution of energy in the Octave (1) the frequency of the noise can be divided into:• Wide band noise
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