Filter Design for Real-Time Ambisonics Encoding During Wave- based Acoustic Simulations

Iain Henderson, Archontis Politis, Stefan Bilbao

Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional


The ambisonics format is a powerful audio tool designed for spatial encoding of the pressure field. An under-exploited feature of this format is that it can be directly extracted from virtual acoustics simulations. Finite Difference Time Domain (FDTD) simulations are particularly adapted as they simplify greatly the problem of extracting spatially-encoded signals, and enable real-time processing of the simulated pressure field. In this short contribution, we first write a time domain representation of the ambisonics channels, in terms of spatial derivatives of the acoustic field at the receiver location, and formulated as a set of ordinary differential equations. We show that in general, the natural corresponding discrete recursive integration yields a prohibitive polynomial drift in time. We then describe a real-time filtering strategy which stabilizes this numerical integration; in the discrete-time setting of FDTD simulations, this real-time filtering process features very low computational costs, avoiding the latency associated with large convolutions and frequency-domain block processing of previous approaches.
Original languageEnglish
Title of host publicationProceedings of the Forum Acusticum 2020
PublisherEAA European Acoustics Association
Number of pages5
Publication statusPublished - Dec 2020
Publication typeD3 Professional conference proceedings
EventForum Acusticum - Lyon, France
Duration: 7 Dec 202011 Dec 2020


ConferenceForum Acusticum


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