Active Noise Control Over Space: A Wave Domain Approach

Abstract

Noise control and cancellation over a spatial region is a fundamental problem in acoustic signal processing. In this paper, we utilize wave-domain adaptive algorithms to iteratively calculate the secondary source driving signals and to cancel the primary noise field over the control region. We propose wavedomain active noise control algorithms based on two minimization problems, (i) minimizing the wave-domain residual signal coefficients and (ii) minimizing the acoustic potential energy over the region, and derive the update equations with respect to two variables, (a) the loudspeaker weights and (b) wave-domain secondary source coefficients. Simulation results demonstrate the effectiveness of the proposed algorithms, more specifically the convergence speed and the noise cancellation performance in terms of the noise reduction level and acoustic potential energy reduction level over the entire spatial region.

Active Noise Control over Space: A Subspace Method for Performance Analysis

“…In literature, both time-domain [7,8] and frequency-domain [9,10] algorithms have been implemented in multichannel ANC systems, which can cancel the noise at error sensor positions and their close surroundings [10]. Recently, ANC over space has been approached via Wave field synthesis (WFS)-based wave-domain algorithms [11][12][13] and (cylindrical/spherical) harmonic-based wave-domain algorithms [14][15][16][17][18][19], with which the noise over entire region of interest can be cancelled directly. Here onwards, we use the terminology 'wave-domain ANC' to refer to harmonics-based wave-domain ANC.…”

“…In wave-domain ANC, the number of secondary sources/loudspeakers is required to be no less than the number of modes in the spatial region, so that all the modes can be controlled. When the number of loudspeakers cannot control all the modes in the spatial region, using the wave-domain adaptive algorithms and conventional adaptive algorithms, the noise reduction performance in the steady state degrades significantly [16]. In practical applications, numbers and locations of the loudspeakers have more constraints compared to simulation setups in [16].…”

“…When the number of loudspeakers cannot control all the modes in the spatial region, using the wave-domain adaptive algorithms and conventional adaptive algorithms, the noise reduction performance in the steady state degrades significantly [16]. In practical applications, numbers and locations of the loudspeakers have more constraints compared to simulation setups in [16]. For instance, in a vehicle, the numbers and positions of the loudspeakers are highly constrained by the vehicle dimensions and passenger convenience.…”

“…In most applications, the number of loudspeakers is less than the requirement. Then the driving signals can be designed by least squares solutions in (16). Therefore, this method is here called the 'wave-domain least squares method' (WDLS).…”

Active control of outgoing noise fields in rooms

“…7,8 The spherical harmonics are powerful tools for sound field analysis and sound field reproduction, 9,10 shedding light on spatial noise field control problems. 7,8,11,12 The main drawback of most existing ANC systems in rooms is that these systems have not explicitly taken additional objects, such as people and desired sound sources, into consideration. The additional objects cause two problems for ANC systems in rooms.…”