Isotropy in decaying reverberant sound fields

Nolan, Mélanie; Berzborn, Marco; Fernández-Grande, Efrén

doi:10.1121/10.0001769

Cited by 21 publications

(13 citation statements)

References 22 publications

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“…A clearly anisotropic decay with additionally decreasing isotropy during the decay was identified in some reverberation room configurations. 30 A similar study of the isotropy condition in the decaying sound field was presented by Nolan et al 31 Alary et al 32 used a slightly modified version of the method presented in Berzborn and Vorländer 29 for the analysis of sound fields in a narrow corridor as well as a church captured with a 32-channel spherical microphone array (SMA).…”

Section: Introductionmentioning

confidence: 99%

Directional sound field decay analysis in performance spaces

Berzborn

Vorländer

2021

Building Acoustics

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The analysis of the spatio-temporal features of sound fields is of great interest in the field of room acoustics, as they inevitably contribute to a listeners impression of the room. The perceived spaciousness is linked to lateral sound incidence during the early and late part of the impulse response which largely depends on the geometry of the room. In complex geometries, particularly in rooms with reverberation reservoirs or coupled spaces, the reverberation process might show distinct spatio-temporal characteristics. In the present study, we apply the analysis of directional energy decay curves based on the decomposition of the sound field into a plane wave basis, previously proposed for reverberation room characterization, to general purpose performance spaces. A simulation study of a concert hall and two churches is presented uncovering anisotropic sound field decays in two cases and highlighting implications for the resulting temporal evolution of the sound field diffuseness.

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Section: Introductionmentioning

confidence: 99%

Directional sound field decay analysis in performance spaces

Berzborn

Vorländer

2021

Building Acoustics

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“…For instance, as the perceptual importance of salient early reflections (ERs) is well known [1], special care is usually given to their reproduction [2], while the late reverberation is often reduced to decaying stochastic noise [3]. Indeed, while never fully realized in practice, the diffusion of sound energy in a room over time tends to lead to a more homogeneous and isotropic distribution [4]. In an opera hall, the orchestral pit and the large area behind the main stage form a coupled volume with the seating area of the hall and their distinct decay characteristics creates an anisotropic sound field [5].…”

Section: Introductionmentioning

confidence: 99%

“…In multichannel reproduction, delay networks are commonly used to create sets of decorrelated signals, each decaying towards a unique reverberation time, thus assuming an isotropic sound field. However, rooms lacking good diffusion properties exhibit inhomogeneous and anisotropic decay of sound [4], [15]. Recent work has proposed novel ways to analyze decaying sound fields [16]- [19] while directional decay char-acteristics have also been found to be perceptually important once a certain threshold is met [20], [21].…”

Section: Introductionmentioning

confidence: 99%

A Method for Capturing and Reproducing Directional Reverberation in Six Degrees of Freedom

Alary

Välimäki

2021

2021 Immersive and 3D Audio: From Architecture to Automotive (I3DA)

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The reproduction of acoustics is an important aspect of the preservation of cultural heritage. A common approach is to capture an impulse response in a hall and auralize it by convolving an input signal with the measured reverberant response. For immersive applications, it is typical to acquire spatial impulse responses using a spherical microphone array to capture the reverberant sound field. While this allows a listener to freely rotate their head from the captured location during reproduction, delicate considerations must be made to allow a full six degrees of freedom auralization. Furthermore, the computational cost of convolution with a high-order Ambisonics impulse response remains prohibitively expensive for current real-time applications, where most of the resources are dedicated towards rendering graphics. For this reason, simplifications are often made in the reproduction of reverberation, such as using a uniform decay around the listener. However, recent work has highlighted the importance of directional characteristics in the late reverberant sound field and more efficient reproduction methods have been developed. In this article, we propose a framework that extracts directional decay properties from a set of captured spatial impulse responses to characterize a directional feedback delay network. For this purpose, a data set was acquired in the main auditorium of the Finnish National Opera and Ballet in Helsinki from multiple source-listener positions, in order to analyze the anisotropic characteristics of this auditorium and illustrate the proposed reproduction framework.

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“…Gover et al used PWD beamforming in [18] to estimate the angular distribution and anisotropy index of the spatial sound field from the RIRs recorded by a spherical microphone array. The recent works in [22][23][24] allow similar analysis in terms of isotropy measures and directional energy decays using Schroeder integration [25] and PWD of directional RIRs. However, these methods require a large number of RIR measurements for an accurate analysis of the room acoustic field.…”

Section: Introductionmentioning

confidence: 99%

Power Response and Modal Decay Estimation of Room Reflections from Spherical Microphone Array Measurements Using Eigenbeam Spatial Correlation Model

2021

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Modal decays and modal power distribution in acoustic environments are key factors in deciding the perceptual quality and performance accuracy of audio applications. This paper presents the application of the eigenbeam spatial correlation method in estimating the time-frequency-dependent directional reflection powers and modal decay times. The experimental results evaluate the application of the proposed technique for two rooms with distinct environments using their room impulse response (RIR) measurements recorded by a spherical microphone array. The paper discusses the classical concepts behind room mode distribution and the reasons behind their complex behavior in real environments. The time-frequency spectrum of room reflections, the dominant reflection locations, and the directional decay rates emulate a realistic response with respect to the theoretical expectations. The experimental observations prove that our model is a promising tool in characterizing early and late reflections, which will be beneficial in controlling the perceptual factors of room acoustics.

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Isotropy in decaying reverberant sound fields

Cited by 21 publications

References 22 publications

Directional sound field decay analysis in performance spaces

Directional sound field decay analysis in performance spaces

A Method for Capturing and Reproducing Directional Reverberation in Six Degrees of Freedom

Power Response and Modal Decay Estimation of Room Reflections from Spherical Microphone Array Measurements Using Eigenbeam Spatial Correlation Model

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