Measurement, Analysis, and Denoising of Directional Room Impulse Responses in Complex Spaces

Abstract

The use of directional room impulse responses (DRIR) measured with spherical microphone arrays (SMA) has become widespread in the reproduction of spatial effects on surround-sound systems through multichannel convolution. However, the measurement of such DRIRs in real-world conditions is inevitably subject to several risk factors, including the presence of a nondecaying noise floor that can produce an infinite reverberation effect when convolved with an input sound. Recent work has focused on model-based techniques for removing this noise floor by replacing it with a re-synthesized prolongation of the measured tail, which has concurrently led to the development of a framework for the spatial analysis of properties. We present here a comprehensive evaluation of the proposed techniques through their application to DRIRs measured in particularly complex spaces, including spatially anisotropic late tails as well as multipleslope decays characteristic of coupled-volume configurations. Following a brief review of the theoretical underpinnings of the tail re-synthesis denoising procedure, the measurement, treatment, analysis, and subsequent denoising of these DRIRs are each detailed and assessed with quantitative metrics. Finally, a discussion of the anisotropic, direction-dependent analysis results obtained is included as the basis for a wider research question on the acoustical considerations behind a stochastic model allowing for spatial variations.