69-05: Fan Noise Levels in Cooling Towers

In this discussion, the word "noise" will refer to any undesirable air-borne sound, and "vibration" will apply to induced motion in mechanical components. We cannot always separate these two phenomena in our discussion, since mechanical vibration is usually a source of sound and is often part of a means by which sound is transmitted. If we make quantitative measurements, we recognize that noise instruments use microphones, detection motion of air, while vibration instruments detect motion in solid objects.