Variable Directivity for Platonic Sound Sources Based on Spherical Harmonics Optimization

Pollow, Martin; Behler, Gottfried

doi:10.3813/aaa.918240

Cited by 33 publications

(26 citation statements)

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“…[4][5][6][7]. More recently, spherical arrays with independently controlled transducers were used as sources featuring adjustable directivity [8][9][10][11][12]. Spatial computer music applied such sources to produce focused beams of sound, e.g.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Auditory Objects Caused by Directional Sound Sources in Rooms

Zotter

Frank

2015

Acta Phys. Pol. A

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The auditory impression of sound sources is strongly influenced by the room, which, e.g., determines the apparent source width. What is more, typical sources are not omnidirectional, which also makes their orientation a strong influence. This influence, however, has only been investigated a little, although it can even change the perceived location of the source. To provide more insight, we performed extensive listening experiments inside our anechoic laboratory that is equipped with a 24-channel loudspeaker playback to simulate both the directional source and the room. The directional source is described by two frequency-independent 3rd order directivity designs in 36 different orientations, and the room is simulated by the two-dimensional 1st and 2nd order image source method. Results of the experiment indicate that, in most cases, the auditory location can be determined by the loudest unmasked acoustic reflection path. This allows to explain the primary direction perceived with an astonishingly simple model including precedence effects.

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Section: Introductionmentioning

confidence: 99%

Investigation of Auditory Objects Caused by Directional Sound Sources in Rooms

Zotter

Frank

2015

Acta Phys. Pol. A

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“…(7). As far as a PSL is concerned, C possesses only Q distinct entries due to the geometrical features summarized in Table II, which are arranged here in a vector a 2 R Q whose ith element is…”

Section: A Arm #1mentioning

confidence: 99%

“…These results have been obtained by modeling each driver membrane as a convex spherical cap that oscillates with a constant radial velocity amplitude over its surface. This simplification has been widely adopted to predict the sound radiation from a spherical loudspeaker array in the low-frequency range, 4,7,8,26,35 but the real vibration pattern and shape of the drivers diaphragms lead to inaccurate results as frequency increases. 18 Thus, the question arises whether the observed frequency independence of the ARMs holds for actual PSLs or it is a consequence of the spherical cap assumption.…”

Section: Introductionmentioning

confidence: 99%

“…These devices have been used since the nineties 1,2 and have found applications in the reproduction of the directivity of musical instruments, 3,4 electroacoustic music, 5 measurement of room impulse responses for auralization purposes, 6,7 and active control of sound, 8 but other applications might be sought. 9 Recently, some academic works dealing with this topic have appeared, [10][11][12][13][14][15] which shed light on the potential and shortcomings of compact loudspeaker arrays, and investigate efficient basis for directivity representation, such as that formed by the spherical harmonics and, less often, by the acoustic radiation modes (ARMs).…”

Section: Introductionmentioning

confidence: 99%

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On the acoustic radiation modes of compact regular polyhedral arrays of independent loudspeakers

Pasqual¹,

Martin²

2011

The Journal of the Acoustical Society of America

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Compact spherical loudspeaker arrays can be used to provide control over their directivity pattern. Usually, this is made by adjusting the gains of preprogrammed spatial filters corresponding to a finite set of spherical harmonics, or to the acoustic radiation modes of the loudspeaker array. Unlike the former, the latter are closely related to the radiation efficiency of the source and span the subspace of the directivities it can produce. However, the radiation modes depend on frequency for arbitrary distributions of transducers on the sphere, which yields complex directivity filters. This work focuses on the most common loudspeaker array configurations, those following the regular shape of the Platonic solids. It is shown that the radiation modes of these sources are frequency independent, and simple algebraic expressions are derived for their radiation efficiencies. In addition, since such modes are vibration patterns driven by electrical signals, the transduction mechanism of compact multichannel sources is also investigated, which is an important issue, especially if the transducers interact inside a shared cabinet. For Platonic solid loudspeakers, it is shown that the common enclosure does not lead to directivity filters that depend on frequency.

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“…Since height invariant reproduction is less applicable in practical scenarios, we consider 3D reproduction employing more realizable three dimensional higher order loudspeakers. These loudspeakers are arrays of transducers independently driven to produce variable directivity patterns up to orderN [15][16][17].…”

Section: Relation To Prior Workmentioning

confidence: 99%

3D soundfield reproduction using higher order loudspeakers

Samarasinghe

Poletti

Salehin

et al. 2013

2013 IEEE International Conference on Acoustics, Speech and Signal Processing

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Three dimensional surround sound reproduction over large areas is a prevailing challenge due to the enormous numbers of loudspeakers required. In this paper, we propose an array of higher order loudspeakers which provide a mode matching solution to the problem based on 3D wavefield translation. It is shown that for a given bandwidth, the use of L th order sources significantly brings down the minimum loudspeaker requirement by a factor of 1/(L + 1)2 . Furthermore, the array is shown to be capable of exterior field cancellation, increasing its performance in echoing environments. Design examples are given for interior field, exterior field and interior and exterior combined field reproduction.

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Variable Directivity for Platonic Sound Sources Based on Spherical Harmonics Optimization

Cited by 33 publications

References 0 publications

Investigation of Auditory Objects Caused by Directional Sound Sources in Rooms

Investigation of Auditory Objects Caused by Directional Sound Sources in Rooms

On the acoustic radiation modes of compact regular polyhedral arrays of independent loudspeakers

3D soundfield reproduction using higher order loudspeakers

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