Technical Paper
Quieting Heavy Machinery with Noise Cancellation Technology
1992-04-01
920921
Environmental noise has been a problem since the industrial revolution. Noise affects our health and safety, interferes with communication, and reduces our ability to enjoy life at its fullest. High frequency noise and vibration have been amenable to passive controls. It has proven difficult to passively control low frequency (500 HZ and below) noise and vibration. The application of Active Noise Cancellation to the control of low frequency noise was proposed over 50 years ago but at that time it was quite impractical. Recent advances in computer technology, however, have now made it a practical solution to many previously difficult problems in environmental noise. This technology does not mask the noise. Noise is reduced by generating a canceling anti-noise signal that is equal to, but 180˚ out of phase with, the noise. This anti-noise is then introduced into the environment such that it matches the noise in the region of interest.
