Combined wave and ray based room acoustic simulations of audio systems in car passenger compartments, Part I: Boundary and source data

Aretz, Marc; Vorländer, Michael

doi:10.1016/j.apacoust.2013.07.021

Cited by 21 publications

(8 citation statements)

References 20 publications

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“…A more reliable estimation may be achieved by a p-u probe measuring sound pressure as well as surface velocity on a surface directly [12]. However, the method requires a time-consuming calibration procedure and seems to be sensitive to reflections from neighbouring surfaces [13].…”

Section: Introductionmentioning

confidence: 99%

In-situ impedance and absorption coefficient measurements using a double-layer microphone array

Hald¹,

Song²,

Haddad³

et al. 2019

Applied Acoustics

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Acoustic impedance is typically measured using an impedance tube, which requires a material sample physically fitted to the tube. However, the impedance can vary greatly between the material mounted in the tube and the material located in a real environment, where the mounting conditions are likely to be different. Also, oblique incidence cannot be measured in an impedance tube. In this paper, we investigate the use of a double-layer microphone array for in-situ measurement of surface impedance and absorption coefficient. With the array positioned near the material surface, a source emits broad-band sound towards the array and the material. A measurement is taken, and the sound pressure and the surface-normal particle velocity at the material surface are calculated using Statistically Optimized Near-field Acoustical Holography (SONAH). From the surface pressure and velocity, the impedance across a selected area is calculated, and finally the absorption coefficient is calculated from the impedance. A set of tests has been performed on porous material samples in an anechoic chamber as well as in a fitted room. Different sample sizes and different sound incidence angles have been considered. The results show consistency between the measurements in the anechoic room and the ordinary room as well as good agreement with Miki's model up to large oblique incidence angles.

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Section: Introductionmentioning

confidence: 99%

In-situ impedance and absorption coefficient measurements using a double-layer microphone array

Hald¹,

Song²,

Haddad³

et al. 2019

Applied Acoustics

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show abstract

“…The low modal density in the low frequency region (green) means it must be handled by a 'wave' solver, such as BEM. 'Hybrid' approaches [9,[12][13][14] do what Figure 1a depicts, that is, run a wave solver for low frequencies and GA for higher frequencies. But this is while efficient, it is not as straightforward as it seems due to the requirement for a crossover between the impulse responses generated by two algorithms (red line).…”

Section: Visionmentioning

confidence: 99%

A comparison between the high-frequency Boundary Element Method and Surface-Based Geometrical Acoustics

Hargreaves

2023

inter noise

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The audible frequency range covers many octaves in which the wavelength changes from being large with respect to dominant features of a space to being comparatively much smaller. This makes numerical prediction of a space's acoustic response, e.g. for auralisation, extremely challenging if all frequencies are to be represented accurately. Different classes of algorithm give the best balance of accuracy to computational cost in different frequency bands - 'wave solvers' such as Boundary Element Method (BEM) at low frequencies and Geometrical Acoustics (GA) methods at high frequencies. But combining their output data can be an awkward process due to their very different formulations. This is particularly important for early reflections, which give crucial spatial perceptual cues. Hence there is a need for a unified full audible bandwidth algorithm for early reflections. This paper will describe ongoing research to develop such an algorithm by exploiting synergies between high-frequency BEM and GA. It will describe how appropriately chosen oscillatory basis functions in BEM can produce leading-order GA behaviour at high frequencies and explore how interactions between these compare to the same interactions arising in a surface-based Geometrical Acoustics scheme.

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“…The surface impedance of the concrete walls is determined based on random incidence absorption coefficients found in the literature which are converted to the locally reacting, real valued surface impedance using the following formula [24],…”

Section: Surface Impedance Of the Concrete Wallsmentioning

confidence: 99%

Experimental validation and uncertainty quantification in wave-based computational room acoustics

et al. 2021

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Combined wave and ray based room acoustic simulations of audio systems in car passenger compartments, Part I: Boundary and source data

Cited by 21 publications

References 20 publications

In-situ impedance and absorption coefficient measurements using a double-layer microphone array

In-situ impedance and absorption coefficient measurements using a double-layer microphone array

A comparison between the high-frequency Boundary Element Method and Surface-Based Geometrical Acoustics

Experimental validation and uncertainty quantification in wave-based computational room acoustics

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