Impact of multiple reflections on urban acoustics

Abstract Understanding how the urban form contributes to noise is important for the successful acoustic design of cities. The amplification of sound is mainly due to the multiple reflections that occur between the high and parallel walls of urban canyons. This study explores the use of ray tracing at the urban scale through the measurement and simulation of three configurations. These are referred to as “1D”, “2D” and “3D”. Impulse response measurements performed at points located on the top of the façades show an increase of 6 dB for the “2D” case and 11 dB for the “3D” case. These results are consistent with ray tracing simulations. This kind of simulation is useful to determine the influence of the street aspect ratio on the sound level. Since specular reflections are related to geometry, a spatialized representation is proposed and discussed.

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Channel Impulse Response at 60 GHz and Impact of Electrical Parameters Properties on Ray Tracing Validations

Electronics ◽

10.3390/electronics10040393 ◽

2021 ◽

Vol 10 (4) ◽

pp. 393

Author(s):

Huthaifa Obeidat ◽

Atta Ullah ◽

Ali AlAbdullah ◽

Waqas Manan ◽

Omar Obeidat ◽

...

Keyword(s):

Electrical Properties ◽

Ray Tracing ◽

Impulse Response ◽

Line Of Sight ◽

Indoor Propagation ◽

60 Ghz ◽

Environment Design ◽

Electrical Parameters ◽

Concrete Walls ◽

Properties Of Materials

This paper outlines a study of the effect of changing the electrical properties of materials when applied in the Wireless InSite (WI) ray-tracing software. The study was performed at 60 GHz in an indoor propagation environment and supported by Line of Sight (LoS) and Non-LoS measurements data. The study also investigates other factors that may affect the WI sensitivity, including antenna dimensions, antenna pattern, and accuracy of the environment design. In the experiment, single and double reflections from concrete walls and wooden doors are analysed. Experimental results were compared to those obtained from simulation using the WI. It was found that materials selected from the literature should be similar to those of the environment under study in order to have accurate results. WI was found to have an acceptable performance provided certain conditions are met.

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Room impulse response simulation based on equal-area ray tracing

2014 International Conference on Audio, Language and Image Processing ◽

10.1109/icalip.2014.7009911 ◽

2014 ◽

Cited By ~ 1

Author(s):

Chengcun Gu ◽

Mengyao Zhu ◽

Haofeng Lu ◽

Benoit Beckers

Keyword(s):

Ray Tracing ◽

Impulse Response ◽

Equal Area ◽

Simulation Based

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Acoustical Design Study on Application of Absorption Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.711.546 ◽

2014 ◽

Vol 711 ◽

pp. 546-549

Author(s):

Wei Lin ◽

Wei Hwa Chiang

Keyword(s):

Computer Simulation ◽

Energy Distribution ◽

Ray Tracing ◽

Impulse Response ◽

Background Noise ◽

Three Dimensional ◽

Design Phase ◽

Design Study ◽

Sound Energy ◽

Reinforcement System

Taipei Top Church Auditorium is a hall primarily intended for praise and worship. A three dimensional ray tracing computer simulation was used to provide sound energy distribution on the audience area of the hall, realistic design have been performed. The volume of the hall is 24600m3, which is occupied for 2200 people and equipped the hall with acoustical curtains by modifying its acoustical characteristics. Objective measurements of impulse response are reported, and background noise control and noise isolation are also be considered in the design phase. Reinforcement system is conducted to meet all the activity for the acoustical environments.

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A ray tracing algorithm for multiple reflections by flat plates, and multiple diffractions by straight wedges and vertexes

2014 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium) ◽

10.1109/usnc-ursi.2014.6955550 ◽

2014 ◽

Author(s):

Federico Puggelli ◽

Giorgio Carluccio ◽

Matteo Albani

Keyword(s):

Ray Tracing ◽

Multiple Reflections ◽

Flat Plates ◽

Tracing Algorithm

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Comparing Higher-dimensional Velocity Models for Seismic Location Accuracy using a Consistent Travel Time Framework

10.5194/egusphere-egu21-926 ◽

2021 ◽

Author(s):

Michael Begnaud ◽

Sanford Ballard ◽

Andrea Conley ◽

Patrick Hammond ◽

Christopher Young

Keyword(s):

Travel Time ◽

Ray Tracing ◽

Seismic Velocity ◽

3D Seismic ◽

Location Accuracy ◽

Velocity Models ◽

Higher Dimensional ◽

1D Model ◽

Tracing Algorithm ◽

2D And 3D

Historically, location algorithms have relied on simple, one-dimensional (1D, with depth) velocity models for fast, seismic event locations. The speed of these 1D models made them the preferred type of velocity model for operational needs, mainly due to computational requirements. Higher-dimensional (2D-3D) seismic velocity models are becoming more readily available from the scientific community and can provide significantly more accurate event locations over 1D models. The computational requirements of these higher-dimensional models tend to make their operational use prohibitive. The benefit of a 1D model is that it is generally used as travel-time lookup tables, one for each seismic phase, with travel-time predictions pre-calculated for event distance and depth. This simple, lookup structure makes the travel-time computation extremely fast.Comparing location accuracy for 2D and 3D seismic velocity models tends to be problematic because each model is usually determined using different inversion parameters and ray-tracing algorithms. Attempting to use a different ray-tracing algorithm than used to develop a model almost always results in poor travel-time prediction compared to the algorithm used when developing the model.We will demonstrate that using an open-source framework (GeoTess, www.sandia.gov/geotess) that can easily store 3D travel-time data can overcome the ray-tracing algorithm hurdle. Travel-time lookup tables (one for each station and phase) can be generated using the exact ray-tracing algorithm that is preferred for a specified model. The lookup surfaces are generally applied as corrections to a simple 1D model and also include variations in event depth, as opposed to legacy source-specific station corrections (SSSCs), as well as estimates of path-specific travel-time uncertainty. Having a common travel-time framework used for a location algorithm allows individual 2D and 3D velocity models to be compared in a fair, consistent manner.

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Transformation to zero offset in transversely isotropic media

Geophysics ◽

10.1190/1.1444044 ◽

1996 ◽

Vol 61 (4) ◽

pp. 947-963 ◽

Cited By ~ 14

Author(s):

Tariq Alkhalifah

Keyword(s):

Ray Tracing ◽

Impulse Response ◽

Homogeneous Medium ◽

Anisotropy Parameter ◽

Transversely Isotropic ◽

Anisotropic Media ◽

Amplitude Distribution ◽

Isotropic Media ◽

Zero Offset ◽

Vertical Inhomogeneity

Nearly all dip‐moveout correction (DMO) implementations to date assume isotropic homogeneous media. Usually, this has been acceptable considering the tremendous cost savings of homogeneous isotropic DMO and considering the difficulty of obtaining the anisotropy parameters required for effective implementation. In the presence of typical anisotropy, however, ignoring the anisotropy can yield inadequate results. Since anisotropy may introduce large deviations from hyperbolic moveout, accurate transformation to zero‐offset in anisotropic media should address such nonhyperbolic moveout behavior of reflections. Artley and Hale’s v(z) ray‐tracing‐based DMO, developed for isotropic media, provides an attractive approach to treating such problems. By using a ray‐tracing procedure crafted for anisotropic media, I modify some aspects of their DMO so that it can work for v(z) anisotropic media. DMO impulse responses in typical transversely isotropic (TI) models (such as those associated with shales) deviate substantially from the familiar elliptical shape associated with responses in homogeneous isotropic media (to the extent that triplications arise even where the medium is homogeneous). Such deviations can exceed those caused by vertical inhomogeneity, thus emphasizing the importance of taking anisotropy into account in DMO processing. For isotropic or elliptically anisotropic media, the impulse response is an ellipse; but as the key anisotropy parameter η varies, the shape of the response differs substantially from elliptical. For typical η > 0, the impulse response in TI media tends to broaden compared to the response in an isotropic homogeneous medium, a behavior opposite to that encountered in typical v(z) isotropic media, where the response tends to be squeezed. Furthermore, the amplitude distribution along the DMO operator differs significantly from that for isotropic media. Application of this anisotropic DMO to data from offshore Africa resulted in a considerably better alignment of reflections from horizontal and dipping reflectors in common‐midpoint gather than that obtained using an isotropic DMO. Even the presence of vertical inhomogeneity in this medium could not eliminate the importance of considering the shale‐induced anisotropy.

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