Influence of impedance phase angle on sound pressures and reverberation times in a rectangular room

Jeong, Cheol‐Ho; Lee, Doheon; Santurette, Sébastien; Ih, Jeong‐Guon

doi:10.1121/1.4861839

Cited by 8 publications

(3 citation statements)

References 38 publications

(59 reference statements)

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“…In the area of beam tracing method, some recent works [31][32][33] focused on the influence of boundary conditions on the prediction results. In the work of Siltanen et al [ 34], they presented a way to introduce incoherent reflections in a beam tracer algorithm.…”

Section: Geometrical Acoustical Methodsmentioning

confidence: 99%

Recent advances in building acoustics: An overview of prediction methods and their applications

Mak

Wang

2015

Building and Environment

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Section: Geometrical Acoustical Methodsmentioning

confidence: 99%

Recent advances in building acoustics: An overview of prediction methods and their applications

Mak

Wang

2015

Building and Environment

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“…In either case, these differences may be audible to some listeners, since the just-noticeable-difference for broadband signals is 0.5-1 dB. 24,25 It is interesting to note that the correlation between error and SPL is present at other frequencies as well, particularly at 33, 51, 68, 86, and 103 Hz for model 1. The higher error is less pronounced for model 4 ( 0 < 0.5 dB from 20 to 100 Hz).…”

Section: A Spl and Accuracymentioning

confidence: 98%

Interference effects in phased beam tracing using exact half-space solutions

Boucher

Pluymers

Desmet

2016

The Journal of the Acoustical Society of America

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Geometrical acoustics provides a correct solution to the wave equation for rectangular rooms with rigid boundaries and is an accurate approximation at high frequencies with nearly hard walls. When interference effects are important, phased geometrical acoustics is employed in order to account for phase shifts due to propagation and reflection. Error increases, however, with more absorption, complex impedance values, grazing incidence, smaller volumes and lower frequencies. Replacing the plane wave reflection coefficient with a spherical one reduces the error but results in slower convergence. Frequency-dependent stopping criteria are then applied to avoid calculating higher order reflections for frequencies that have already converged. Exact half-space solutions are used to derive two additional spherical wave reflection coefficients: (i) the Sommerfeld integral, consisting of a plane wave decomposition of a point source and (ii) a line of image sources located at complex coordinates. Phased beam tracing using exact half-space solutions agrees well with the finite element method for rectangular rooms with absorbing boundaries, at low frequencies and for rooms with different aspect ratios. Results are accurate even for long source-to-receiver distances. Finally, the crossover frequency between the plane and spherical wave reflection coefficients is discussed.

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“…Jeong (2012) investigated real and complex-valued boundary conditions using the phased beam tracing method and found that the impedance phase angle affects the sound pressure level. In the study of Jeong et al (2014), the phased beam tracing method was used to investigate the perceived reverberance for the wall impedance with different phase angles. It was found that, for uniform absorption settings, the non-zero impedance phase angle results in a perceptual difference in reverberance when compared to a zero-phase impedance.…”

Section: Introductionmentioning

confidence: 99%

Archives of Acoustics

2022

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Accurate definition of boundary conditions is of crucial importance for room acoustic predictions because the wall impedance phase angle can affect the sound field in rooms and acoustic parameters applied to assess a room reverberation. In this paper, the issue was investigated theoretically using the convolution integral and a modal representation of the room impulse response for complex-valued boundary conditions. Theoretical considerations have been accompanied with numerical simulations carried out for a rectangular room. The case of zero phase angle, which is often assumed in room acoustic simulations, was taken as a reference, and differences in the sound pressure level and decay times were determined in relation to this case. Calculation results have shown that a slight deviation of the phase angle with respect to the phase equal to zero can cause a perceptual difference in the sound pressure level. This effect was found to be due to a change in modal frequencies as a result of an increase or decrease in the phase angle. Simulations have demonstrated that surface distributions of decay times are highly irregular, while a much greater range of the early decay time compared to the reverberation time range indicates that a decay curve is nonlinear. It was also found that a difference between the decay times predicted for the complex impedance and real impedance is especially clearly audible for the largest impedance phase angles because it corresponds approximately to 4 just noticeable differences for the reverberation metrics.

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Influence of impedance phase angle on sound pressures and reverberation times in a rectangular room

Cited by 8 publications

References 38 publications

Recent advances in building acoustics: An overview of prediction methods and their applications

Recent advances in building acoustics: An overview of prediction methods and their applications

Interference effects in phased beam tracing using exact half-space solutions

Archives of Acoustics

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