Abstract
Spatial room impulse responses (SRIRs) measured using spherical microphone arrays are seeing increasingly widespread use in reproducing room reverberation effects on three-dimensional surround sound systems (e.g., higher-order ambisonics) through multi-channel SRIR convolution. However, such measured impulse responses inevitably present a non-negligible noise floor, which may lead to a perceptible "infinite reverberation effect" when convolved with an input sound. Furthermore, individual sensor noise and momentary measurement artefacts may additionally corrupt the resulting impulse response. This paper presents a robust SRIR denoising procedure applicable to impulse responses with diffuse late reverberation tails, which can be modeled by a stochastic process. In such cases, the non-decaying frequency-dependent noise floor may be replaced by a synthesized incoherent tail parameterized by the SRIR's energy decay envelope. It is shown that performing such tail re-synthesis in the spherical harmonic domain, using an independent zero-mean Gaussian noise for each component, preserves both the reverberation tail's frequency-dependent decay as well as its spatial coherence properties. The proposed process is then evaluated through its application to SRIRs measured in real-world conditions, and finally some aspects of performance and consistency verification are discussed.
Highlights
INTRODUCTIONSpherical microphone arrays (SMAs) enable the directional analysis of a given sound field by sampling it over the
The re-synthesis of the late reverberation tail is evaluated here in two steps: the consistency of the energy decay relief (EDR) analysis is first verified on deliberately noised simulations, and results obtained on an spatial room impulse response (SRIR) measured in real-world conditions are subsequently presented
This paper has addressed the problem of removing the non-decaying noise floor inevitably present in SRIRs measured with Spherical microphone arrays (SMAs) and replacing it with a valid extension of the exponentially-decaying late reverberation tail
Summary
Spherical microphone arrays (SMAs) enable the directional analysis of a given sound field by sampling it over the. X2S2 where X 1⁄4 ðh; /Þ is a point on the surface of a sphere with fixed radius r 1⁄4 a [in conformity with ISO 8000-2:2009(E) (2009)], xðf ; X; tÞ is the time-frequency domain representation of the sound field on the sphere, and Yl;mðXÞ are the spherical harmonics of order l 2 Zþ and degree m 2 1⁄2Àl; l. This transform defines the SHD signal coefficients Xl;mðf ; tÞ for each component or mode (l, m). Such is the case in the widespread higher-order ambisonics format, where the center of the sphere is used as the reference point and for which the correcting filters are determined (Daniel and Moreau, 2004)
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