초록 ▼

An active attenuator is provided for the attenuation of a relatively broad band of lower frequency vibration such as sound waves from a given source, by the introduction of cancelling vibration having the mirror image amplitude and phase characteritics of the source vibration. The active attenuator

An active attenuator is provided for the attenuation of a relatively broad band of lower frequency vibration such as sound waves from a given source, by the introduction of cancelling vibration having the mirror image amplitude and phase characteritics of the source vibration. The active attenuator herein includes an input sensor for detecting the source vibration, a cancelling speaker for generating cancelling vibration, an error sensor for sensing the combination of source and cancelling vibration, and an electronic controller coupled to the input sensor, cancelling speaker and error sensor. The electronic controller includes an adaptive cancelling filter which employs a deterministic algorithm operable to accommodate the propagation delays of the vibration sensed by the input and error sensors, and produce an output to activate and control the cancelling speaker for the production of cancelling vibration.

대표청구항 ▼

Apparatus for the attenuation of sound from a source propagating in a duct comprising: input sensing means for detecting said source sound, said input sensing means producing first electrical signals representing the amplitude and phase characteristics of said source sound; cancelling means for gene

Apparatus for the attenuation of sound from a source propagating in a duct comprising: input sensing means for detecting said source sound, said input sensing means producing first electrical signals representing the amplitude and phase characteristics of said source sound; cancelling means for generating cancelling sound, said cancelling sound being introduced into said duct for combination with and attenuation of said source sound; error sensing means for detecting said combination of said cancelling sound and source sound, said error sensing means producing second electrical signals representing the amplitude and phase characteristics of said combination of said cancelling sound and source sound, the production of said second electrical signals by said error sensing means being delayed in time relative to the production of said first electrical signals by said input sensing means due to the time of propagation of said source sound from said input sensing means to said cancelling means and the time of propagation of said source sound and cancelling sound to said error sensing means; and electronic controller means coupled to said input sensing means, cancelling means and error sensing means for activating and controlling said cancelling means to produce said cancelling sound, said electronic controller means including an adaptive cancelling filter employing a modified deterministic algorithm operable to accommodate said acoustic propagation delays.