A Technique for Measuring Acoustic Noise from Power Equipment (NOT PUBLISHED)

Power equipment has had a history of emitting acoustic noise caused by mechanical vibrations produced in the equipment structure by current- induced magnetic fields. A sound of low magnitude and low frequency (300Hz) is perceived by the human ear as a dull "hum" that is often indistinguishable from ambient noise. However power equipment using Ferroresonant technology can emit a high magnitude of sound at low as well as relatively high frequencies which are higher harmonics of the fundamental frequency (60Hz). This can be very irritating to personnel in the vicinity particularly because power equipment typically emit sound monotonously.