Active sound absorbers in an air duct

Jessel, Maurice; Mangiante, Gerard

doi:10.1016/0022-460x(72)90633-5

Cited by 88 publications

(34 citation statements)

References 1 publication

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“…VðsÞ À BlIðsÞ EðsÞ ¼ ðsL e þ R e ÞIðsÞ À BlVðsÞ ( ; (3) where P þ (s), V(s), E(s), and I(s) are the Laplace transforms of p þ (t), v(t), e(t), and i(t), respectively, and…”

Section: A General Presentationmentioning

confidence: 99%

“…The formal introduction of the concept of sound absorption by electroacoustic means can be attributed to Olson and May, 2 who applied a feedback control on a loudspeaker, based on sound pressure sensing. In the footsteps of this novel formulation of active noise control, Jessel et al 3 studied the principle of active absorbers in the light of formal analogies with the Huygens theory of sound propagation, leading to practical requirements of the secondary sound sources. Guicking 4 extended the concept to an hybrid structure combining an acoustic passive absorber with an active electroacoustic transducer.…”

Section: Introductionmentioning

confidence: 99%

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Electroacoustic absorbers: Bridging the gap between shunt loudspeakers and active sound absorption

Lissek

Boulandet

Fleury

2011

The Journal of the Acoustical Society of America

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The acoustic impedance at the diaphragm of an electroacoustic transducer can be varied using a range of basic electrical control strategies, amongst which are electrical shunt circuits. These passive shunt techniques are compared to active acoustic feedback techniques for controlling the acoustic impedance of an electroacoustic transducer. The formulation of feedback-based acoustic impedance control reveals formal analogies with shunt strategies, and highlights an original method for synthesizing electric networks ("shunts") with positive or negative components, bridging the gap between passive and active acoustic impedance control. This paper describes the theory unifying all these passive and active acoustic impedance control strategies, introducing the concept of electroacoustic absorbers. The equivalence between shunts and active control is first formalized through the introduction of a one-degree-of-freedom acoustic resonator accounting for both electric shunts and acoustic feedbacks. Conversely, electric networks mimicking the performances of active feedback techniques are introduced, identifying shunts with active impedance control. Simulated acoustic performances are presented, with an emphasis on formal analogies between the different control techniques. Examples of electric shunts are proposed for active sound absorption. Experimental assessments are then presented, and the paper concludes with a general discussion on the concept and potential improvements.

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Section: A General Presentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electroacoustic absorbers: Bridging the gap between shunt loudspeakers and active sound absorption

Lissek

Boulandet

Fleury

2011

The Journal of the Acoustical Society of America

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“…component due to the modeling signal , and denotes the linear convolution. The desired response for the adaptive FBPM filter is given as (4) where is an estimate of obtained through FBPM filter (5) where is the impulse response of , is the tap-weight length of , and is the -sample output signal vector. It is important to note that there is one sample delay in appearance of acoustic feedback at the reference microphone [1], as shown in Fig.…”

Section: Existing Methods For Online Feedback Path Modelingmentioning

confidence: 99%

“…A literature review shows that there are following ways to overcome the problem of acoustic feedback. 1) To use directional microphones and loudspeakers, and to place the components so that the acoustic feedback can be avoided [5]- [12]. These techniques are expensive, and often the performance is quite limited.…”

Section: Introductionmentioning

confidence: 99%

On Active Noise Control Systems With Online Acoustic Feedback Path Modeling

Akhtar

Abe

Kawamata

2007

IEEE Trans. Audio Speech Lang. Process.

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Abstract-The presence of strong acoustic feedback degrades the convergence speed of the active noise control (ANC) filter, and in the worst case the ANC system may become unstable. A fixed feedback neutralization filter, obtained offline, can be used to neutralize the acoustic feedback. The feedback path, however, may be time varying, and we may need continual adjustments during online operation of the ANC system. This paper proposes a new method for online modeling of the acoustic feedback path in ANC systems. The proposed method uses three adaptive filters; a noise control filter, a feedback path modeling (FBPM) filter, and an adaptive noise cancelation (ADNC) filter. The objective of ADNC filter is to remove the disturbance from the desired response of FBPM filter. In comparison with the existing method, which works only for predicable noise sources, the proposed method can work, as well, with the broadband noise sources. The computer simulations are carried out for narrowband (predictable) (case I) and broadband (random) noise sources (case II). It is demonstrated that the proposed method performs better than the existing method in both cases.Index Terms-Acoustic feedback, active noise control (ANC), FxLMS algorithm, online feedback path modeling.

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“…S': primary source of noise F': primary field (radiated by S') S": secondary source(s), introduced either by Huygens Principle or by the Principle of Active Absorption1) F": secondary field (radiated by S") OP: "Physical" operator connecting a field F with its source(s): OP F = S (hence also : OP F'= S' and OP F"= S") OR: "Radiation" operator expressing a field F in terms of its source(s): OR S = F (hence also : F' = OR S' and F" = OR S") 1 passive attenuation is well developed and is extensively employed in mufflers, absorptive wall panels and damping coatings for vibrating structures. The absorption efficiency for a given passive device generally increases with the frequency of the noise; and for frequencies above 300 Hz, passive absorption is the usual and cheapest solution.…”

Section: Vocabulary Notations and Abbreviationsmentioning

confidence: 99%