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Analysis of Directional Room Impulse Responses (DRIRs)

Authors Keller, B.
Year 2014
Thesis Type Audio Engineering project
Topic Spatial Audio
Abstract For several decades, reverberation processors have been based on feedback delay networks (FDN) that provide an efficient way to control the distribution of early reflections and the statistical properties of room reverberation. Recent research has shown an increasing interest in the spatial analysis of room acoustics, which can be employed to transfer the rich and complex sound fields of certain venues or concert halls to other locations. The spatial acoustic information is typically captured with microphone arrays and extracted into Directional Room Impulse Responses (DRIRs). Convolving monophonic audio signals with DRIRs allows for creating playback signals distinct by a certain acoustic impression. The playback signals can be processed for Higher Order Ambisonics (HOA), headphone-based binaural sound synthesis using Head Related Transfer Functions (HRTFs) or any other consumer playback standard with their specific limitations. Using smart algorithms the computational load can be limited so that rendering the signals in real time becomes possible. Recent developments in the control of high-level perceptual descriptors rather than low-level signal processing parameters let convolution based room simulators become the successor to feedback delay networks (FDN). This work discusses the spherical wave spectral representation and processing of DRIRs measured with spherical microphone arrays. We present a novel method for denoising measured DRIRs, which is based on previous work of IRCAM's EAC research group. Computational optimizations for real-time implementations will be discussed.
Supervisors Noisternig, M.