Local active control of diffracted diffuse sound fields

García-Bonito, J.; Elliott, Stephen J.

doi:10.1121/1.413666

Cited by 33 publications

(28 citation statements)

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“…The presence of a rigid sphere affects the secondary sound field by imposing zero particle velocity, and thus zero pressure gradient. As has been shown by Garcia-Bonito and Elliott, this results in a beneficial flattening of the secondary field which tends to increase the spatial extent of the quiet zone close to the head [31]. In addition, it has been found for the studied configuration that increasing the size of the diaphragm loudspeaker is beneficial to increase the size of the quiet zone, as already observed by Joseph et al in the case of a single secondary loudspeaker and a single point in its near field.…”

Section: Discussionmentioning

confidence: 70%

Design of Remote Quiet Zones Using Spot-Type Sound Reducers

Boulandet¹,

Laurence²,

Lissek³

2017

Acta Acustica united with Acustica

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SummaryThis paper presents a local control approach to generate remote quiet zones. To deal with situations where global control can hardly be achieved, it is proposed to use an arrangement of spot-type sound reducers as originally suggested by Olson and May. Assuming that cross-coupling between control units is weak, each can be controlled independently and a decentralised feedback controller is implemented without the need for direct monitoring of the primary source. Active noise attenuation in the remote target region is achieved using a linear quadratic optimization based on prior knowledge of the transfer path of the system. The performance of a particular configuration comprising three control units is examined by numerical simulation and experimentally evaluated for a tonal noise source in a free-field environment. An average noise reduction of about 6 dB was measured in a target region of volume 0.25 × 0.25 × 0.25 m 3 for a 160 Hz tonal primary source distant more than one wavelength from the secondary sources. The performance of the control system in relation to changes in the primary field is also considered with a view to extending the concept to more realistic enclosed sound field conditions in future work.

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Section: Discussionmentioning

confidence: 70%

Design of Remote Quiet Zones Using Spot-Type Sound Reducers

Boulandet¹,

Laurence²,

Lissek³

2017

Acta Acustica united with Acustica

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“…25 This optimisation problem has been solved using sequential quadratic programming, which is possible since the cost function is convex and the constraints are affine, 26 although other programming methods may also be used. 22 To ensure that the solution to the discrete problem given by equation 7 approximates the desired solution to the continuous problem it is important that K is large enough, such that the discretised frequency responses are accurately represented.…”

Section: Controller Optimisationmentioning

confidence: 99%

The Design and Performance of Feedback Controllers for the Attenuation of Road Noise in Vehicles

Cheer¹,

Elliott²

2014

IJAV

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Active noise control systems offer a potential method of reducing the weight of acoustic treatments in vehicles and, therefore, of increasing fuel efficiency. The commercialisation of active noise control has not been widespread, however, partly due to the cost of implementation. This paper investigates the design and performance of feedback road noise control systems, which could be implemented cost-effectively by using the car audio loudspeakers as control sources and low-cost microphones as error sensors. Three feedback control systems are investigated, of increasing complexity: a single-input single-output (SISO) controller; a SISO controller employing weighted arrays of error sensors and control sources; and a fully-coupled multi-input multi-output (MIMO) controller. For each of the three controllers robustness and disturbance enhancement constraints are defined and by formulating the three controllers using an Internal Model Control (IMC) architecture, and using frequency discretisation, the constrained optimisation problems are solvable using sequential quadratic programming. The performance of the three controllers and the associated design methods are first evaluated in a simulated environment, which allows the physical limits on performance to be understood. Finally, to validate the results in the simulated environment, the performance of the three controllers has been calculated using data measured in a car cabin and it has been shown that the fully-coupled MIMO controller is able to achieve significant low frequency road noise control, at the expense of increased implementation complexity compared to the SISO and SISO weighted transducer arrays feedback controllers.

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“…12. Although the general formulation could include the effects of diffraction around finite-sized secondary sources, and the head, in the definition of the transfer responses, 20,21 these effects are not included in the simulations presented here, so as to more clearly illustrate the principles of the method. The optimum control problem is first formulated in the frequency domain, to explore the geometrical limitations of control for relatively narrowband disturbances, but a time-domain formulation is also included for the calculation of causal broadband controllers.…”

Section: Introductionmentioning

confidence: 99%

Modeling local active sound control with remote sensors in spatially random pressure fields

Elliott

Cheer

2015

The Journal of the Acoustical Society of America

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A general formulation is presented for the optimum controller in an active system for local sound control in a spatially random primary field. The sound field in a control region is selectively attenuated using secondary sources, driven by reference sensors, all of which are potentially remote from this control region. It is shown that the optimal controller is formed of the combination of a leastsquares estimation of the primary source signals from the reference signals, and a least-squares controller driven by the primary source signals themselves. The optimum controller is also calculated using the remote microphone technique, in both the frequency and the time domains. The sound field under control is assumed to be stationary and generated by an array of primary sources, whose source strengths are specified using a spectral density matrix. This can easily be used to synthesize a diffuse primary field, if the primary sources are uncorrelated and far from the control region, but can also generate primary fields dominated by contributions from a particular direction, for example, which is shown to significantly affect the shape of the resulting zone of quiet.

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Local active control of diffracted diffuse sound fields

Cited by 33 publications

References 0 publications

Design of Remote Quiet Zones Using Spot-Type Sound Reducers

Design of Remote Quiet Zones Using Spot-Type Sound Reducers

The Design and Performance of Feedback Controllers for the Attenuation of Road Noise in Vehicles

Modeling local active sound control with remote sensors in spatially random pressure fields

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