Absorption and impedance boundary conditions for phased geometrical-acoustics methods

Jeong, Cheol‐Ho

doi:10.1121/1.4740494

Cited by 20 publications

(24 citation statements)

References 21 publications

(41 reference statements)

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“…46 Rindel suggested a method for estimating the angle dependence of the reflection factor from the random incidence a s by assuming a real-valued impedance, 47 and an evaluation of the use of impedance vs absorption coefficient boundary conditions was presented by Jeong. 46 …”

Section: Infinite Flat Surfacesmentioning

confidence: 99%

Overview of geometrical room acoustic modeling techniques

Savioja¹,

Svensson

2015

The Journal of the Acoustical Society of America

287

190

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Computerized room acoustics modeling has been practiced for almost 50 years up to date. These modeling techniques play an important role in room acoustic design nowadays, often including auralization, but can also help in the construction of virtual environments for such applications as computer games, cognitive research, and training. This overview describes the main principles, landmarks in the development, and state-of-the-art for techniques that are based on geometrical acoustics principles. A focus is given to their capabilities to model the different aspects of sound propagation: specular vs diffuse reflections, and diffraction.

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Section: Infinite Flat Surfacesmentioning

confidence: 99%

Overview of geometrical room acoustic modeling techniques

Savioja¹,

Svensson

2015

The Journal of the Acoustical Society of America

287

190

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“…II B is no longer valid. 40,41 For impulse response measurements, the microphone is moved by the negative incident angle, keeping the distance between microphone and the absorber center constant at 0.8 m. For the array measurements, a planar array with 60 pressure microphones is placed at horizontal x-y planes above the absorber independent of the angle of incidence. The measurements are performed for three different planes, z h1 ¼ 4 cm, z h2 ¼ 8 cm, and z h3 ¼ 6 cm; see Fig.…”

Section: ) At Incident Angles H ¼ F0mentioning

confidence: 99%

In situ measurements of the oblique incidence sound absorption coefficient for finite sized absorbers

Ottink

Brunskog

Jeong

et al. 2016

The Journal of the Acoustical Society of America

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Absorption coefficients are mostly measured in reverberation rooms or with impedance tubes. Since these methods are only suitable for measuring the random incidence and the normal incidence absorption coefficient, there exists an increasing need for absorption coefficient measurement of finite absorbers at oblique incidence in situ. Due to the edge diffraction effect, oblique incidence methods considering an infinite sample fail to measure the absorption coefficient at large incidence angles of finite samples. This paper aims for the development of a measurement method that accounts for the finiteness of the absorber. A sound field model, which accounts for scattering from the finite absorber edges, assuming plane wave incidence is derived. A significant influence of the finiteness on the radiation impedance and the corresponding absorption coefficient is found. A finite surface method, which combines microphone array measurements over a finite sample with the sound field model in an inverse manner, is proposed. Besides, a temporal subtraction method, a microphone array method, impedance tube measurements, and an equivalent fluid model are used for validation. The finite surface method gives promising agreement with theory, especially at near grazing incidence. Thus, the finite surface method is proposed for further measurements at large incidence angles.

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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%