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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.
Characteristics of Sound Waves. Sounds are generally audible to the human ear if their frequency (number of vibrations per second) lies between 20 and 20,000 vibrations per second, but the range varies considerably with the individual.