The active minimization of harmonic enclosed sound fields, part II: A computer simulation

Bullmore, A.J.; Nelson, P.A.; Curtis, A. R.; Elliott, Stephen J.

doi:10.1016/0022-460x(87)90433-0

Cited by 95 publications

(49 citation statements)

References 1 publication

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“…1. The main difference between the current analysis and the previous ones in this field [20,21] is that the dimensions of the selected enclosure are proper multiplies of each other. This property will result in some degenerate modes in the analysis, and this will complicate the control action.…”

Section: Modal Description Of Enclosurementioning

confidence: 91%

“…This property will result in some degenerate modes in the analysis, and this will complicate the control action. In [20] with the Modal Analysis for Global Control of Broadband Noise in a Rectangular Enclosure assumption that the variations of mode shapes are negligible in comparison with other two dimensions, the problem is studied in a two dimensional case, and in [21] the dimensions of enclosure are chosen such that each resonance frequency corresponds to one mode shape, and hence there are no degenerate modes. The solution of (1) with boundary conditions in (2) can be expressed in terms of some basic functions, called the acoustical modes of enclosure.…”

Section: Modal Description Of Enclosurementioning

confidence: 99%

See 1 more Smart Citation

Modal Analysis for Global Control of Broadband Noise in a Rectangular Enclosure

Montazeri

Poshtan

Kahaei

2007

Journal of Low Frequency Noise, Vibration and Active Control

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Modal analysis for examination of the possibility of the global reduction of broadband noise in a rectangular enclosure has been studied in this paper. By developing a modal model of the acoustic environment of the enclosure the shape modes and their frequencies are obtained and on suitable bandwidth for the controller design is calculated. In order to simplify the analysis the noise sources are assumed localized and internal in one corner of the kiosk. The analysis results show that due to the existence of some degenerate modes in this application, the control action is complicated. Simulation results demonstrate how positions and number of loudspeakers and microphones will change the performance of the controller and its corresponding control effort. Based on these results and analysis a reasonable size for the controller and proper locations for sensors and actuators are proposed. Simulation results also confirm the effectiveness of the proposed system in reduction of the acoustic potential energy in the kiosk.

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Section: Modal Description Of Enclosurementioning

confidence: 91%

Section: Modal Description Of Enclosurementioning

confidence: 99%

Modal Analysis for Global Control of Broadband Noise in a Rectangular Enclosure

Montazeri

Poshtan

Kahaei

2007

Journal of Low Frequency Noise, Vibration and Active Control

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“…where a P shows the effect of the primary source on the amplitude of acoustic modes, is a matrix whose element B nm shows the effect of the mth source on the nth mode, and q s is the vector of volume velocities of secondary sources [2] and Appendix A. By substituting Eq.…”

Section: Problem Statement and Modeling Of The Kioskmentioning

confidence: 99%

“…(1), the amplitude of complex pressure at a specific point and frequency can be obtained as In Eq. (3), ψ n (x) is the nth mode shape of the enclosure, and a n (ω) is its amplitude [2] and Appendix A. By truncation of Eq.…”

Section: Problem Statement and Modeling Of The Kioskmentioning

confidence: 99%

Optimizing a Multi-Channel ANC System for Broadband Noise Cancellation in a Telephone Kiosk Using Genetic Algorithms

Montazeri

Poshtan

2009

Shock and Vibration

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Abstract. The problem of optimizing an active noise control system for the implementation of a multi-channel ANC system with the aim of global reduction of broadband noise in a telephone kiosk is addressed in this paper. This optimization involves finding best locations for loudspeakers and microphones, and optimizing control signals. The problem of finding a proper size for control system, i.e. the number of loudspeakers and microphones involved in the control system is also investigated. The mean of acoustic potential energy in the enclosure in a frequency range of 50 Hz to 300 Hz is selected as a measure for optimization. Several genetic algorithms are proposed and compared to find the global minimum of this performance index. In order to have a better performance in reaching the global minimum, the parameters of these genetic algorithms are tuned, and the best genetic algorithm is selected among them. Numerical simulations of the acoustical potential energy and also sound pressure at the height where the head of a person may be located, confirms the optimality of the locations proposed by the genetic algorithm. Besides, the robustness of the optimized control system with respect to eventual changes in the location of primary and secondary loudspeakers and also microphones is shown with several simulations.

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“…For this purpose, the conventional modal sum of the sound field in a lightly damped rectangular enclosure with walls of uniform specific acoustic admittance proposed by Morse 22 is used in the form presented by Bullmore et al 23 The sources are modeled as square pistons that vibrate with a normal velocity u l = q l / A, where A = a 2 is the area of the piston sources. The piston sources are oriented inside the room so that their surfaces are parallel to the xz-plane.…”

Section: B Conditions For the Simulationsmentioning

confidence: 99%

Regularization in global sound equalization based on effort variation

Stefanakis

Sarris

Jacobsen

2009

The Journal of the Acoustical Society of America

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Sound equalization in closed spaces can be significantly improved by generating propagating waves that are naturally associated with the geometry, as, for example, plane waves in rectangular enclosures. This paper presents a control approach termed effort variation regularization based on this idea. Effort variation equalization involves modifying the conventional cost function in sound equalization, which is based on minimizing least-squares reproduction errors, by adding a term that is proportional to the squared deviations between complex source strengths, calculated independently for the sources at each of the two walls perpendicular to the direction of propagation. Simulation results in a two-dimensional room of irregular shape and in a rectangular room with sources randomly distributed on two opposite walls demonstrate that the proposed technique leads to smaller global reproduction errors and better equalization performance at listening positions outside of the control region compared to effort regularization and compared to a simple technique that involves driving groups of sources identically.

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The active minimization of harmonic enclosed sound fields, part II: A computer simulation

Cited by 95 publications

References 1 publication

Modal Analysis for Global Control of Broadband Noise in a Rectangular Enclosure

Modal Analysis for Global Control of Broadband Noise in a Rectangular Enclosure

Optimizing a Multi-Channel ANC System for Broadband Noise Cancellation in a Telephone Kiosk Using Genetic Algorithms

Regularization in global sound equalization based on effort variation

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