Novel metrics for characterization of surfaces for sound scattering and beam steering

• Applicants: Professorin Dr. Sigrid Brell-Cokcan; Professor Dr. Michael Vorländer
• Subject Area: Acoustics ; City Planning, Spatial Planning, Transportation and Infrastructure Planning, Landscape Planning
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 456072683

This project focuses on novel acoustic descriptors for architectural surfaces. The approach as such is relevant for all indoor and outdoor environments but it is focused on building façades. Building façades play a vital role in the acoustic part of urban planning. They reflect and scatter the incident sound which can lead to positive and negative effects on the sound, often perceived as noise, at the immission points. Different scales of building facades are divisible into micro scale (material of the surface, which is slightly related to geometric design rules), macro scale (for example surface patterns and cladding panels) and building elements (such as the arrangement of balconies, windows and doors), which makes the situation rather complex, particularly when it comes to various frequencies. With standard methods of acoustic engineering only the diffuse (Lambert) scattering or the specular reflection is modelled. Back scattering models for specific surface structures do not exist, so that for example retroreflection or other phenomena of sound beam steering cannot be considered in planning. An application on building facades could be to steer the noise to where it does not cause disturbance. The goal of this project is to extent the information depth of surface reflection and scattering effects in form of a novel set of acoustic surface metrics (“scattering coefficient 2.0”) and to provide database structures of the new metrics for surface patterns. These metrics are then implemented in a Virtual Reality demonstrator of future acoustic simulation algorithms. For architecture, parametric design and fabrication rules for sound steering surfaces will be developed.

• DFG Programme: Research Grants