A realization of sound focused personal audio system using acoustic contrast control

Since the mid 1990s, acoustics research has been undertaken relating to the sound zone problem-using loudspeakers to deliver a region of high sound pressure while simultaneously creating an area where the sound is suppressed-in order to facilitate independent listening within the same acoustic enclosure. The published solutions to the sound zone problem are derived from areas such as wave field synthesis and beamforming. However, the properties of such methods differ and performance tends to be compared against similar approaches. In this study, the suitability of energy focusing, energy cancelation, and synthesis approaches for sound zone reproduction is investigated. Anechoic simulations based on two zones surrounded by a circular array show each of the methods to have a characteristic performance, quantified in terms of acoustic contrast, array control effort and target sound field planarity. Regularization is shown to have a significant effect on the array effort and achieved acoustic contrast, particularly when mismatched conditions are considered between calculation of the source weights and their application to the system.

Section: Introductionmentioning

confidence: 99%

Acoustic contrast, planarity and robustness of sound zone methods using a circular loudspeaker array

Coleman

Jackson

Olik

et al. 2014

“…1 Generally, two different kinds of zones are created by the personal audio systems-the bright zone, a region where a desired sound pressure level is reproduced, and the dark zone, where the sound pressure level needs to be attenuated. For this purpose, Choi and Kim 2,3 used the acoustic contrast as a measure of performance and proposed the acoustic contrast control (ACC) approach to maximize this contrast.…”

Section: Introductionmentioning

confidence: 99%

Time-domain acoustic contrast control design with response differential constraint in personal audio systems

Cai

Liu

et al. 2014

The acoustic contrast control (ACC) approach is applied to reproduce the focused sound in personal audio systems utilizing an array of loudspeakers. A time-domain design of ACC is developed here for broadband input signals, where a response differential term is introduced to control the frequency response. Based on experimental results in an anechoic chamber, the proposed method demonstrates the potential capability to provide excellent acoustic contrast over the continuous frequency and maintain a flat frequency response. Furthermore, compared with the previous method, fewer parameters need to be tuned in the proposed method.

“…On the other hand, only a few studies that validate sound field control with loudspeakers experimentally have been published. [10][11][12][13][14][15] These studies have shown that the sound field control is feasible as expected from the simulations, but the exterior region of the loudspeakers array has not been considered.…”

mentioning

confidence: 90%

Experimental validation of sound field control with a circular double-layer array of loudspeakers

Chang

Jacobsen

2013

Self Cite

This paper is concerned with experimental validation of a recently proposed method of controlling sound fields with a circular double-layer array of loudspeakers [Chang and Jacobsen, J. Acoust. Soc. Am. 131(6), 4518–4525 (2012)]. The double-layer of loudspeakers is realized with 20 pairs of closed-box loudspeakers mounted back-to-back. Source strengths are obtained with several solution methods by modeling loudspeakers as a weighted combination of monopoles and dipoles. Sound pressure levels of the controlled sound fields are measured inside and outside the array in an anechoic room, and performance indices are calculated. The experimental results show that a method of combining pure contrast maximization with a pressure matching technique provides only a small error in the listening zone between the desired and the reproduced fields, and at the same time reduces the sound level in the quiet zone as expected in the simulation studies well above the spatial Nyquist frequency except at a few frequencies. It is also shown that errors in the positions of the loudspeakers can be critical to the results at frequencies where the distance between the inner and the outer array is close to half a wavelength.