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

Lissek, Hervé; Boulandet, Romain; Fleury, Romain

doi:10.1121/1.3569707

Cited by 80 publications

(57 citation statements)

References 19 publications

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“…As each mode has its own central frequency, an optimal absorber would have a frequency-dependent specific acoustic resistance that matches these different values. Another form of target specific acoustic impedance could then be preferred to that given by (10). Finally for practical reasons, the total absorbing area should be relatively small compared to the total reflecting area of the room.…”

Section: Application To Roomsmentioning

confidence: 99%

“…In this scheme, it can be clearly seen that the blocked electrical impedance Z e of the loudspeaker is absent from the control. Current drive presents the advantage of discarding Kirchhoff's law (2), thus eliminating the blocked electrical impedance Z e in the equation of the loudspeaker, whereas this quantity can potentially be a source of instability in a voltage drive control configuration [10], [14]. Nevertheless, this strategy requires an accurate evaluation of the loudspeaker mechanical parameters, such as the effective piston area S d , the force factor Bl, and the mechanical impedance (mass M ms , resistance R ms , and compliance C mc ).…”

Section: B Sound Absorption Capabilitymentioning

confidence: 99%

“…The control of parameter µ then extends the bandwidth of efficient sound absorption around this central frequency. It is also conceivable to apply two different reduction factors µ 1 for the mass and µ 2 for the stiffness in (10), to shift the resonance frequency f 0 without modifying the cabinet volume V b 2 .…”

Section: Target Specific Acoustic Impedance For the Diaphragmmentioning

confidence: 99%

“…Alternatively, sensor-based control techniques either require two external sensors [10], [11], but are difficult to use for room applications, or one sensor but requires the design of a constant velocity sound source [12] or the use a velocity estimator [13]. These techniques usually employ a voltage amplifier to drive the loudspeaker, involving the voice-coil inductance in the control, which as a consequence limits the sound absorption performance at higher frequencies.…”

Section: Introductionmentioning

confidence: 99%

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Broadband Low-Frequency Electroacoustic Absorbers Through Hybrid Sensor-/Shunt-Based Impedance Control

Rivet

Karkar

Lissek

2017

IEEE Trans. Contr. Syst. Technol.

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Abstract-This paper proposes a hybrid impedance control architecture for an electroacoustic absorber, that combines an improved microphone-based feedforward control with a currentdriven electrodynamic loudspeaker system. Feedforward control architecture enables stable control to be achieved, and current driving method discards the effect of the voice coil inductance. A method is given for designing the transfer function to be implemented in the controller, according to a target specific acoustic impedance and mechanical parameters of the transducer. Numerical simulations present the expected acoustic performance, introducing global performance indicators such as the bandwidth of efficient absorption. Experimental assessments in a waveguide confirmed the accuracy of the model and the efficiency of the hybrid control technique for achieving broadband, stable lowfrequency electroacoustic absorbers. An application to damping of resonances in a duct is also presented, and the application to the modal equalization in actual listening rooms is finally discussed.

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Section: Application To Roomsmentioning

confidence: 99%

Section: B Sound Absorption Capabilitymentioning

confidence: 99%

Section: Target Specific Acoustic Impedance For the Diaphragmmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Broadband Low-Frequency Electroacoustic Absorbers Through Hybrid Sensor-/Shunt-Based Impedance Control

Rivet

Karkar

Lissek

2017

IEEE Trans. Contr. Syst. Technol.

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“…In this section, a model combining a second order band-pass filter, representing the mute, and a model of the speaker is developed. The loudspeaker model is based on Lissek et al 22 (case 0).…”

Section: Appendix A: Model With Mute and Loudspeakermentioning

confidence: 99%

An active mute for the trombone

Meurisse

Mamou-Mani

Causse

et al. 2015

The Journal of the Acoustical Society of America

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A mute is a device that is placed in the bell of a brass instrument to alter its sound.However, when a straight mute is used with a brass instrument, the frequencies of its first impedance peaks are slightly modified, and a mistuned, extra impedance peak appears. This peak affects the instrument's playability, making some lower notes difficult or impossible to produce when playing at low dynamic levels. To understand and suppress this effect, an active mute with embedded microphone and speaker has been developed. A control loop with gain and phase shifting is used to control the damping and frequency of the extra impedance peak. The stability of the controlled system is studied and then the effect of the control on the input impedance and radiated sound of the trombone is investigated.It is shown that the playability problem results from a decrease in the input impedance magnitude at the playing frequency, caused by a trough located on the low frequency side of the extra impedance peak. When the extra impedance peak is suppressed, the playability of the note is restored. Meanwhile, when the extra impedance peak is moved in frequency, the playability problem position is shifted as well. et al., JASA, p. 3 Meurisse

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Effect of hole on sound absorption coefficient of micro‐perforated panels investigated by Melling computing

Wang

Xiong

2018

Concurrency and Computation

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Microperforated board is one of the important ways to absorb noise. However, the mechanism is still not well understood of the interaction between micropores, and the influence of the distance between the micropores on the sound absorption performance of microperforated plates is still not clarified. Professor Merlin introduced the influence of micropore interaction on the sound absorption performance of microperforated plates. Based on Maa and Melling theory, this paper proposed an absorption coefficient that considers the effect of perforation interactions. In addition, the formula was used to calculate the absorption coefficient and the resonance frequency and, subsequently, was tested by the conducted experiments. The results show that the structure parameters of the micro-perforated panel affect its absorption coefficient, and the model can search the absorption coefficient more efficiently, with the calculated result close to the experimental value. KEYWORDS cavity on the back, micro-perforated panel (MPP), nonlinear, sound absorption coefficient INTRODUCTIONFor decades, the use of micro-perforated panel (MPP), a sound absorbing material placed in front of a rigid wall, has been highly regarded, and a schematic diagram of the structure is shown in Figure 1. As the Figure shown, there exists a gap/cavity between the sound absorbing material and the wall, with many holes on the MPP sheet. MPP provides a high sound absorption coefficient in low frequency ranges and a wider absorption bandwidth, having many advantages such as low cost, light weight, small size solution, and simple structure. Compared with traditional porous materials, MPP can be used not only in outdoor environments but also in indoor surroundings. Moreover, MPP does not cause air pollution but can withstand noise in any environment such as washing, wind, and freezing. Therefore, MPP can be used in the field of noise control and is considered to be a potential absorbing material with ideal effect in the future. For example, the microperforated board with polymer material is an innovative material for absorption noise.The sound absorption principle of the MPP absorber was analyzed by an equivalent circuit model, regarded as one of the more valuable theories.The basic principle was following the Helmholtz resonator, 1 with the parameters such as aperture size, aperture distance, and backing volume. Wan et al, 2 Duval et al, 3 and Mejdi and Atalla 4 established the MPP noise absorption formula based on classical plate equations and acoustic equations, which can explain the vibration effects of acoustic perforation boards. Maury et al 5 also indicated that the MPP structure can be used to amplify the acoustic absorption range, if it was considered as a modal response. Also, the experimental values had a good consistency with model calculated results by combining the characteristics of the rectangular MPP with the tension effect, modeling the air flow resistance. 6 Generally speaking, structural vibrations improve the precision of the model, which i...

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

Cited by 80 publications

References 19 publications

Broadband Low-Frequency Electroacoustic Absorbers Through Hybrid Sensor-/Shunt-Based Impedance Control

Broadband Low-Frequency Electroacoustic Absorbers Through Hybrid Sensor-/Shunt-Based Impedance Control

An active mute for the trombone

Effect of hole on sound absorption coefficient of micro‐perforated panels investigated by Melling computing

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