Time Domain Spherical Harmonic Processing with Open Spherical Microphones Recording

Sun, Huiyuan; Abhayapala, Thushara D.; Samarasinghe, Prasanga N.

doi:10.3390/app11031074

Cited by 3 publications

(1 citation statement)

References 37 publications

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“…Control of the frequency domain causes a delay of the size of at least one FFT block [3]. To solve this problem, a spherical harmonics analysis in the time domain was performed [25,26]. However, the group delay of the finite impulse response filter is inevitable, and this group delay lowers the ANC performance.…”

Section: Simulation Resultsmentioning

confidence: 99%

Horizontal Active Noise Control Based on Wave Field Reproduction Using a Single Circular Array in 3D Space

Kim

et al. 2022

Applied Sciences

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In this paper, we propose horizontal active noise control (ANC) using two-dimensional wave field information alone. By reducing the control space to a horizontal plane, the number of microphones and speakers was considerably reduced compared with ANC systems using three-dimensional wave field information. The radii of the reference, microphone, and loudspeaker array were determined based on the wave field reproduction error. Accordingly, the simulation and experimental results of the proposed ANC system were presented based on the use of five microphones and loudspeakers using conventional ANC algorithms. Overall, an average noise reduction of 20 dB was observed inside the microphone array with a radius of 0.5 m for tonal noise at 200 Hz. This performance is acceptable with a drastically reduced number of microphones and speakers. The findings of this study, along with further research conducted in a reverberant room, represent a significant contribution to global ANC commercialization.

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Section: Simulation Resultsmentioning

confidence: 99%

Horizontal Active Noise Control Based on Wave Field Reproduction Using a Single Circular Array in 3D Space

Kim

et al. 2022

Applied Sciences

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Spherical harmonic representation of the observed directional wave front in the time domain

Wang

Abhayapala

Samarasinghe

et al. 2022

JASA Express Letters

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Sound field reproduction algorithms require loudspeaker directivity, which is usually measured at discrete frequencies. A time domain model of loudspeaker directivity benefits broadband applications. This Letter proposes the concept of a directional wave front in the time domain, which could be linked to loudspeaker impulse responses measured on a spherical surface. The observed signal in the time domain at the boundary of a spherical region due to a propagating directional wave front is illustrated using a geometric model. Based on the geometric model, the spherical harmonic decomposition of the observed signal in the time domain is also derived.

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Time-domain sound field reconstruction using a rigid spherical microphone array

Jiang,

Chu,

Zhao

et al. 2024

The Journal of the Acoustical Society of America

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A time-domain approach for interior spherical near-field acoustic holography is proposed to achieve the low-delay reconstruction of time-domain sound fields using a rigid spherical microphone array. This reconstruction encompasses the incident pressure field, the incident radial particle velocity field, and the total pressure field, which includes scattering. The proposed approach derives time-domain radial propagators through the inverse Fourier transform of their frequency-domain counterparts. These propagators are then applied to the array measurements to obtain the time-domain spherical harmonic coefficients of the interior sound field. Given the fact that the time-domain radial propagators possess finite-time support and exhibit significant high-frequency attenuation characteristics, they can be efficiently implemented using finite impulse response (FIR) filters. The proposed approach processes the signal sample-by-sample through these FIR filters, avoiding a series of issues associated with time-frequency transformations in frequency-domain methods. As a result, the approach offers higher accuracy and lower latency in reconstructing non-stationary sound fields compared to its frequency-domain counterpart and thus holds greater potential for real-time applications. Additionally, owing to the scattering effect of the rigid sphere, the approach avoids the impact of spherical Bessel function nulls and does not require the measurement of particle velocities, which renders the measurements cost effective.

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Time Domain Spherical Harmonic Processing with Open Spherical Microphones Recording

Cited by 3 publications

References 37 publications

Horizontal Active Noise Control Based on Wave Field Reproduction Using a Single Circular Array in 3D Space

Horizontal Active Noise Control Based on Wave Field Reproduction Using a Single Circular Array in 3D Space

Spherical harmonic representation of the observed directional wave front in the time domain

Time-domain sound field reconstruction using a rigid spherical microphone array

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