Sound attenuating system
AssigneesCalsonic Corporation, Nishiwaki Laboratory
InventorsMasao Taki, Takuji Mori, Shuntaro Murakami
Life of this patent
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Abstract
A sound attenuating system for attenuating sound from a sound source. The system comprises a main conduit through which the sound from the sound source propagates; a first device for defining in the conduit at least one passive acoustic reflecting surface; and a second device for defining in the conduit a plurality of active acoustic reflecting surfaces. The active acoustic reflecting surfaces are of a type which permits a partial permeation of sound therethrough.
Claims23
A sound attenuating system for attenuating sound issued from a sound source, comprising:
- a main conduit through which the sound from said sound source propagates;
- a passive silencer operatively installed in said main conduit thereby to define at least two passive acoustic reflecting surfaces at front and rear portions of said passive silencer;
- and
- a pair of branched conduit systems arranged on said passive silencer to define an active acoustic reflecting surface in said passive silencer, each branched conduit system including
- a branched conduit connected to said main conduit,
- a secondary sound source installed in said branched conduit for issuing a secondary sound when driven,
- a sound detecting sensor installed in said branched conduit at a location between said secondary sound source and said main conduit, said sound detecting sensor detecting a reference signal based on a signal from said sound source, and
- a signal processing unit for driving said secondary sound source by processing said reference signal,
- wherein said branched conduit systems are so constructed that said active acoustic reflecting surface thus produced in said passive silencer permits a partial permeation of sound therethrough.
A sound attenuating system for attenuating sound issued from a sound source, comprising:
- a main conduit through which sound from said sound source propagates;
- means for providing in said main conduit at least one passive acoustic reflecting surface;
- a branch conduit extending from a side of said main conduit;
- a sound detecting sensor installed in said branch conduit for detecting a reference signal based on a signal from said sound source;
- a secondary sound source installed in said branch conduit issuing a secondary sound when driven, a distance between said side of said main conduit and said secondary sound source being greater than a distance between said side of said main conduit and said sound detecting sensor;
- and
- a signal processing unit for driving said secondary sound source by processing said reference signal,
- wherein said sound detecting sensor, said secondary sound source and said signal processing unit are arranged such that an active acoustic reflecting surface thus provided in said main conduit permits a partial permeation of sound therethrough.
A method for attenuating sound, comprising the steps of:
- a) propagating sound from a primary source to a passive silencer through a first conduit, said first conduit having a diameter which is smaller than a diameter of said passive silencer;
- b) detecting said sound in said silencer using at least one branched conduit having a microphone;
- c) processing said detected sound to generate a phase reversed signal;
- d) generating sound from a secondary source located in a side of said passive silencer in response to said phase reversed signal, wherein said secondary sound has a phase opposite to that of said sound from said primary source;
- and
- e) propagating any sound not reflected by steps b) through d) from said passive silencer to a second conduit, said second conduit having a diameter which is smaller than a diameter of said passive silencer.
A sound attenuating system connected between first and second portions of a main conduit, said main conduit propagating sound from a sound source through said first portion of said main conduit to said sound attenuating system, said system comprising:
- an expansion chamber positioned between said first and second portions of said main conduit, said expansion chamber receiving said sound propagated from said first portion of said main conduit, a cross-sectional area of said expansion chamber being greater than a cross-sectional area of said first portion of said main conduit;
- at least one passive acoustic reflecting surface;
- a secondary sound source positioned at a side of said expansion chamber;
- a sound detecting sensor positioned between said secondary sound source and a center of said expansion chamber, said sound detecting sensor generating a reference signal;
- and
- a control unit driving said secondary sound source according to said reference signal, wherein said sound detecting sensor, said secondary sound source and said control unit are arranged such that an active acoustic reflecting surface is generated within said expansion chamber.
Dependencies are inferred from the claim text.