A superdirective array of phase shift sources

Gálvez, Marcos F. Simón; Elliott, Stephen J.; Cheer, Jordan

doi:10.1121/1.4733556

Cited by 35 publications

(52 citation statements)

References 16 publications

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“…However, these are not designed to address the degradations to target quality caused by reproducing programs using sound zoning systems. The types of degradations caused by sound zoning systems may include spatial degradations (due to uncontrolled phase and selfcancellation) [11], temporal degradations (such as ringing or pre-echo) [12], spectral coloration, and variation in all of these across the reproduction zone that may be audible with listener head movement.…”

Section: Introductionmentioning

confidence: 99%

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The Relationship Between Target Quality and Interference in Sound Zone

Baykaner¹,

Coleman²,

Mason³

et al. 2015

J. Audio Eng. Soc.

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Sound zone systems aim to produce regions within a room where listeners may consume separate audio programs with minimal acoustical interference. Often, there is a trade-off between the acoustic contrast achieved between the zones and the fidelity of the reproduced audio program (the target quality). An open question is whether reducing contrast (i.e., allowing greater interference) can improve target quality. The planarity control sound zoning method can be used to improve spatial reproduction, though at the expense of decreased contrast. Hence, this can be used to investigate the relationship between target quality (which is affected by the spatial presentation) and distraction (which is related to the perceived effect of interference). An experiment was conducted investigating target quality and distraction and examining their relationship with overall quality within sound zones. Sound zones were reproduced using acoustic contrast control, planarity control, and pressure matching applied to a circular loudspeaker array. Overall quality was related to target quality and distraction, each having a similar magnitude of effect; however, the result was dependent upon program combination. The highest mean overall quality was a compromise between distraction and target quality, with energy arriving from up to 15 degrees either side of the target direction. INTRODUCTIONSound zone systems aim to control sound fields in such a way that multiple listeners can enjoy different audio programs within the same room. Conceptually, the overall quality of the sound zone listening experience could be considered to be the result of some combination of the effect of the presence of an interferer program and the effect of any artifacts or degradations to the target program (i.e., target quality) caused by the sound zone processing. A similar conceptual framework was utilized in [1]. While the relationship between the effect of the interferer and the effect of target quality degradations is unclear, a considerable body of research exists on these topics individually.Fields of research investigating the effect of auditory interferers include: the perception of environmental noise [2,3], the perception of multiple talkers [4], source separation [5], and combinations of these [6]. These studies generally do not consider common domestic interferers, such as music or sound effects in films; and where they do, they either do not isolate the interferer effect or they include artifacts and degradations that may be specific to source separation algorithms.In [7] a series of elicitation experiments were conducted to investigate terms describing auditory interference scenarios using ecologically valid programs (i.e., those that are commonly consumed in domestic environments). The results, and those of [8], showed that using the term "distraction" produced good agreement between listeners, and that listener ratings made using this term were a good measure of the perceived effect of the interferer. It seems likely, therefore, that there would be...

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Section: Introductionmentioning

confidence: 99%

“…Acoustic contrast control (ACC) [13] gives the maximum contrast between the zones but does not attempt to control the phase of the resulting sound field. Least-squares optimization has therefore typically been used when control of the target field is necessary [12,14,18], at the cost of reduced acoustic contrast.…”

Section: Introductionmentioning

confidence: 99%

The Relationship Between Target Quality and Interference in Sound Zone

Baykaner¹,

Coleman²,

Mason³

et al. 2015

J. Audio Eng. Soc.

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“…Personal audio devices are commonly formed by loudspeaker arrays, being adopted in a number of different applications which require a directed sound, for example; in individual sound reproduction using headrest loudspeakers [7] or laptop loudspeakers [8], to restrict the directivity of the sound from mobile phones [9] or to create different sound zones inside a car [10]. The use of a loudspeaker array to create a highly directional sound source and enhance the audio of the TV has been previously considered in terms of the signal processing and electroacoustical tuning of the device [11], using an array of 8 phase-shift sources. The phase-shift sources [12] use an acoustical network to create a hypercardioid directivity pattern which minimises the excitation of the reverberant field [13], thus allowing control of the rear radiation using a reduced number of sources.…”

Section: Introductionmentioning

confidence: 99%

Personal Audio Loudspeaker Array as a Complementary TV Sound System for the Hard of Hearing

Gálvez

Elliott

Cheer

2014

IEICE Trans. Fundamentals

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The usage of this PDF file must comply with the IEICE Provisions on Copyright. The author(s) can distribute this PDF file for research and educational (nonprofit) purposes only. Distribution by anyone other than the author(s) is prohibited. SUMMARYA directional array radiator is presented, the aim of which is to enhance the sound of the television in a particular direction and hence provide a volume boost to improve speech intelligibility for the hard of hearing. The sound radiated by the array in other directions is kept low, so as not to increase the reverberant level of sound in the listening room. The array uses 32 loudspeakers, each of which are in phase-shift enclosures to generate hypercardioid directivity, which reduces the radiation from the back of the array. The loudspeakers are arranged in 8 sets of 4 loudspeakers, each set being driven by the same signal and stacked vertically, to improve the directivity in this plane. This creates a 3D beamformer that only needs 8 digital filters to be made superdirective. The performance is assessed by means of simulations and measurements in anechoic and reverberant environments. The results show how the array obtains a high directivity in a reverberant environment. key words: personal audio, array signal processing, beamforming, hearing aid

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“…where (·) −1 indicates the operation of matrix inversion, and I is the identity matrix of dimensions 13 L × L. In personalized audio applications, the target fieldp for the PM method is commonly 14 defined as [15,20] …”

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confidence: 99%

“…14 The input energy is identical for all the optimal methods across the whole frequency range up 15 to the aliasing frequency. Furthermore, the input energy is equal to E MAX (i.e., 10 log 10 σ = 14 16 dB) at low frequencies (below f 1 ≈ 3.2 kHz), that is the frequency region where the array is small 17 compared to the wavelength and the filters need high input energy to control the sound field.…”

mentioning

confidence: 99%

Theoretical and experimental comparative analysis of beamforming methods for loudspeaker arrays under given performance constraints

Olivieri

Fazi

Nelson

et al. 2016

Journal of Sound and Vibration

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Methods for beamforming are available that provide the signals used to drive an array of sources for the implementation of systems for the so-called personal audio. In this work, performance of the delay-and-sum (DAS) method and of three widely used methods for optimal beamforming are compared by means of computer simulations and experiments in an anechoic environment using a linear array of sources with given constraints on quality of the reproduced field at the listener's position and limit to input energy to the array. Using the DAS method as a benchmark for performance, the frequency domain responses of the loudspeaker filters can be characterized in three regions. In the first region, at low frequencies, input signals designed with the optimal methods are identical and provide higher directivity performance than that of the DAS. In the second region, performance of the optimal methods are similar to the DAS method. The third region starts above the limit due to spatial aliasing. A method is presented to estimate the boundaries of these regions.

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A superdirective array of phase shift sources

Cited by 35 publications

References 16 publications

The Relationship Between Target Quality and Interference in Sound Zone

The Relationship Between Target Quality and Interference in Sound Zone

Personal Audio Loudspeaker Array as a Complementary TV Sound System for the Hard of Hearing

Theoretical and experimental comparative analysis of beamforming methods for loudspeaker arrays under given performance constraints

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