Analysis and Synthesis of Small Room Acoustics

• Applicant: Professor Dr.-Ing. Sebastian Schlecht
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering ; Acoustics
• Term: from 2019 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426805376

Reverberation is an everyday acoustical experience which occurs when sound waves are bouncing back and forth in an enclosed space. Room acoustic features such as room geometry, source and listener positions and boundary materials determine the physical and perceptual properties of the resulting reverberation. In many applications, it is necessary to recreate the reverberation effect artificially. Artificial reverberation can be based on purely physical simulation of room acoustics. However, the required immense computational complexity limits the accuracy depending on the application requirements. Thus, there is a demand for efficient algorithms which are not necessarily physically accurate but which are perceptually convincing. The ASSAI-project aims to investigate techniques for analyzing acoustic features from small room measurements and synthesizing perceptually accurate room impulse responses with a particular focus on a computationally efficient method, i.e., feedback delay network (FDN). FDNs represent a broad class of sparse recursive filters such that the fundamental investigations in this project are relevant to a wide range of digital signal processing applications including decorrelation, numerical sound synthesis, and physical modeling. We introduce two innovative extensions to FDNs: control of room modes and diffusion. To facilitate systematic investigation of the perceptual translation, we propose an end-to-end design from room acoustic measurement to parameter estimation, physical translation, model reduction and evaluation. We focus on small room acoustics because of its particular relevance in applications such as augmented reality, instrument modeling, and movie post-production. The measurements and analysis of the small room acoustics are based on spatial room impulse responses and room geometry depth maps which in turn drives computational acoustic simulations. The FDN is then derived from the physical simulation with a perceptually motivated error measure. The evaluation is performed against real-world references and investigates viability for augmented reality applications.

• DFG Programme: Research Grants
• International Connection: Finland, United Kingdom
• Cooperation Partners: Professor Stefan Bilbao; Professor Vesa Välimäki