Quieting Heavy Machinery with Noise Cancellation Technology 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. The two signals then cancel each other out, effectively removing a significant portion of the noise energy from the environment.
Many applications for this technology exist in heavy machinery. They include:
Active Mufflers - Reduce exhaust noise from internal combustion engines, compressors, and vacuum pumps without the inefficiencies caused by back pressure.
Active Mounts - Contain vibration from rotating machines to improve comfort, decrease wear, and reduce secondary acoustic noise.
Quiet Zones - Silent Seats and Cabin Quieting to provide comfortable workstations for equipment operators.
Active Headsets - Extend hearing protection beyond passive ear defenders to include low frequencies. Active headsets can also be selective to allow communication and improve work place safety.