Leo McCormack, Archontis Politis, and Ville Pulkki

Rendering of source spread for arbitrary playback setups based on spatial covariance matching

Companion page for a paper in the 2021 IEEE Workshop on Applications of Signal Processing to Audio and Acoustics, New York, USA, October 17–21, 2021


In this paper, an algorithm for rendering incoherently spread sound sources over arbitrary playback formats is proposed. The approach involves first generating coherently spread source signals for the intended playback setup, along with decorrelated variants, followed by defining a target diffuse spatial covariance matrix computed over the desired spreading area. The mixing matrices required to combine these prototype signals, in a manner whereby the resulting output signals exhibit the target inter-channel relationships for an incoherent source spreading, are computed based on an optimised solution that is constrained to preserve signal fidelity. The proposed solution is then evaluated in the context of producing sound sources of physical extent for binaural playback. Objective perceptual parameters are computed and compared to those given by an ideal incoherently spread white noise reference. Signal distortion measures are also calculated for speech, musical, and ambience recordings, which indicate higher signal fidelity produced by the proposed constrained spatial covariance matching solution, compared to an unconstrained alternative. These improvements in signal fidelity are further exemplified by the provided audio examples and the accompanying open-source audio plug-in.


The paper can be found on the IEEE publications website.

Audio-plugin example

A VST audio plug-in was developed to demonstrate the proposed source spreading method. It can be downloaded from here, and the source-code for it can be found here.

Sound examples

All of the sound examples can be downloaded from here, or listened to individually below. Note that, for example, 60 degrees of spread refers to a spreading extent based on all HRTF measurements within 30 degrees of the central panning direction.

Binaural example - Drums

Binaural example - Strings

Binaural example - Waves

Binaural example - Seagulls

Binaural example - Speech (male)

Binaural example - Speech (female)

Updated on Wednesday April 21, 2021
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