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2.2 FACTORS AFFECTING PROPAGATION OF SOUND There are several important factors, which affect the propagation of sound: geometric spreading, atmospheric effects, and surface effects. These are discussed separately below. 2.2.1 Geometric Spreading This refers to the spreading of sound energy as a result of the expansion of the wave fronts.
Damage from sound is determined by the loudness of the sound and also by the duration of exposure to the sound. Brief exposure to an 85 dB sound (such as a blender) is O.K. However, prolonged continuous exposure (8 or more hours) to the same sound could damage hearing.