JO - Journal of the Audio Engineering SocietyДЄB - This contribution proposes a simplified rendering of source directivity patterns for the simulation and auralization of auditory scenes consisting of multiple listeners or sources. TI - Simplified Source Directivity Rendering in Acoustic Virtual Reality Using the Directivity Sample Combination The promising results suggest further studies of the proposed simplification in the future to assess its applicability to more complex georg and pulkki, ville}, As a proof of concept, the simplification is evaluated from a technical as well as from a perceptual point of view for one specific use case. This reduces the amount of required filtering operations considerably and thus increases the computational efficiency of the auralization. It is based on applying directivity filters of arbitrary directivity patterns at multiple, supposedly important directions, and approximating the filter outputs of intermediate directions by interpolation. doi:ДЄbstract: This contribution proposes a simplified rendering of source directivity patterns for the simulation and auralization of auditory scenes consisting of multiple listeners or sources. Pulkki, 'Simplified Source Directivity Rendering in Acoustic Virtual Reality Using the Directivity Sample Combination,' Paper 10286, (2019 October.).

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Hopefully, this directivity study provides values not only for railway noise engineering but also for a better understanding of railway noise. With all these outputs integrated, a survey of the directivities of all important railway noise sources has been achieved and applicable directivity functions have been worked out. Finally, to complete directivity description of railway noise, directivities of other important noise types have been studied as well the directivity characteristics of these noise types become understood although lack the relevant directivity data. And, once again, scattered fluid sound around the bogie areas and turbulent boundary layer noise along the train side surfaces can be treated as a PDP source. This understanding leads to a different directivity description for this noise component. Moreover, for aerodynamic noise around bogie areas, scattering of the air flow was proposed to be the dominant mechanism of the noise generation. As for aerodynamic noise, it has been found that pantograph noise is also of perpendicular dipole components.

This model naturally explains why rail radiation is of different horizontal and vertical directivities and why a vibrating railway wheel does not present dipole directivity. As for wheel/rail radiation, a model of a perpendicular dipole pair (PDP) was proposed to interpret those measurement specified directivity characteristics. Directivities of these two noise types are studied based on measurement investigation, theoretical problem solution and model analysis. The study focuses on the two most important railway noise types, i.e. This thesis work aims at working out an applicable directivity description of railway noise sources. All these factors increase difficulties in reaching a proper directivity description that may explain why modelling directivities of railway noise sources is so far behind modelling their sound powers. Moreover, it is a question if the horizontal directivity of a line source can be measured directly. As for railway noise engineering, several noise types of different directivity characteristics are often mixed together, such as wheel and rail radiation, engine and cooling fan noise, scattered fluid sound around the bogie areas and turbulent boundary layer noise along the train side surfaces. However, in practice, this is often not a simple procedure. Therefore, to reach a proper directivity description is in fact a process of understanding the sound source in a better way. For example, turbulence sound is of quadrupole directivity whilst fluid-structure interaction often induces a sound of dipole characteristic.

This parameter also reflects the physical feature of the sound generation mechanism. Applicable directivity description of railway noise sourcesДЇor a sound source, directivity is an important parameter to specify.

Model noise with directivity in cadnaa