Silencer attenuating a noise from a noise source to be ventilated and a method for active control of its noise attenuation system

摘要

A silencer attenuating a noise from a noise source to be ventilated of this invention comprises a machine compartment with a one-dimensional duct configuration whose sectional dimension is sufficiently small in comparison with the wavelength of the noise to be attenuated, a compressor and/or other machinery disposed within the machine compartment, an opening for dissipation of heat as disposed in a wall of the machine compartment and opening in a direction generally perpendicular to the direction of advance of sound within the machine compartment, a vibration pickup for detecting the vibration of the machinery corresponding to the output noise of the machinery, and a control circuit for processing output signals from the vibration pickup to drive a sound generator such as a speaker. The sound generator outputs a controlling signal dependent on the machine noise to cancel the noise about to emerge from the machine compartment.