Direct and Residual Subspace Decomposition of Spatial Room Impulse Responses

Psychoacoustic experiments have shown that directional properties of the direct sound, salient reflections, and the late reverberation of an acoustic room response can have a distinct influence on the auditory perception of a given room. Spatial room impulse responses (SRIRs) capture those properties and thus are used for direction-dependent room acoustic analysis and virtual acoustic rendering. This work proposes a subspace method that decomposes SRIRs into a direct part, which comprises the direct sound and the salient reflections, and a residual, to facilitate enhanced analysis and rendering methods by providing individual access to these components. The proposed method is based on the generalized singular value decomposition and interprets the residual as noise that is to be separated from the other components of the reverberation. Large generalized singular values are attributed to the direct part, which is then obtained as a low-rank approximation of the SRIR. By advancing from the end of the SRIR toward the beginning while iteratively updating the residual estimate, the method adapts to spatio-temporal variations of the residual. The method is evaluated using a spatio-spectral error measure and simulated SRIRs of different rooms, microphone arrays, and ratios of direct sound to residual energy. The proposed method creates lower errors than existing approaches in all tested scenarios, including a scenario with two simultaneous reflections. A case study with measured SRIRs shows the applicability of the method under real-world acoustic conditions. A reference implementation is provided

Perceptual Evaluation of Spatial Room Impulse Response Extrapolation by Direct and Residual Subspace Decomposition

Six-degrees-of-freedom rendering of an acoustic environment can be achieved by interpolating a set of measured spatial room impulse responses (SRIRs). However, the involved measurement effort and computational expense are high. This work compares novel ways of extrapolating a single measured SRIR to a target position. The novel extrapolation techniques are based on a recently proposed subspace method that decomposes SRIRs into a direct part, comprising direct sound and salient reflections, and a residual. We evaluate extrapolations between different positions in a shoebox-shaped room in a multi-stimulus comparison test. Extrapolation using a residual SRIR and salient reflections that match the reflections at the target position is rated as perceptually most similar to the measured reference

Spatial Subtraction of Reflections from Room Impulse Responses Measured With a Spherical Microphone Array

We propose\ua0a\ua0method for the decomposition of\ua0measured\ua0directional\ua0room\ua0impulse\ua0responses\ua0(DRIRs) into prominent\ua0reflections\ua0and\ua0a\ua0residual. The method comprises obtaining\ua0a\ua0fingerprint of the time-frequency signal that\ua0a\ua0given\ua0reflection\ua0carries, imposing this time-frequency fingerprint on\ua0a\ua0plane-wave prototype that exhibits the same propagation direction as the\ua0reflection, and finally subtracting this plane-wave prototype from the DRIR. Our main contributions are the formulation of the problem as\ua0a\ua0spatial\ua0subtraction\ua0as well as the incorporation of order truncation,\ua0spatial\ua0aliasing and regularization of the radial filters into the definition of the underlying beamforming problem. We demonstrate, based on simulated as well as\ua0measured\ua0array\ua0impulse\ua0responses, that our method increases the accuracy of the model of the\ua0reflection\ua0under test and consequently decreases the energy of the residual that remains in\ua0a\ua0measured\ua0DRIR after the\ua0spatial\ua0subtraction

Perceptual Evaluation of Spatial Room Impulse Response Extrapolation by Direct and Residual Subspace Decomposition

Six-degrees-of-freedom rendering of an acoustic environment can be achieved by interpolating a set of measured spatial room impulse responses (SRIRs). However, the involved measurement effort and computational expense are high. This work compares novel ways of extrapolating a single measured SRIR to a target position. The novel extrapolation techniques are based on a recently proposed subspace method that decomposes SRIRs into a direct part, comprising direct sound and salient reflections, and a residual. We evaluate extrapolations between different positions in a shoebox-shaped room in a multi-stimulus comparison test. Extrapolation using a residual SRIR and salient reflections that match the reflections at the target position is rated as perceptually most similar to the measured reference

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