# Real-time separation of non-stationary sound fields on spheres

## TL;DR

This paper introduces a real-time, time-domain sound field separation method on spheres that effectively isolates non-stationary sound sources in noisy environments, outperforming traditional frequency-domain approaches.

## Contribution

A novel time-domain separation technique for non-stationary sound fields on spheres, enabling real-time processing and broader applicability in dynamic acoustic scenarios.

## Key findings

- Effective separation of non-stationary sound fields demonstrated in simulations.
- Works in both free field and room environments.
- Maintains accuracy over longer durations with minimal errors.

## Abstract

The sound field separation methods can separate the target field from the interfering noises, facilitating the study of the acoustic characteristics of the target source, which is placed in a noisy environment. However, most of the existing sound field separation methods are derived in the frequency-domain, thus are best suited for separating stationary sound fields. In this paper, a time-domain sound field separation method is developed that can separate the non-stationary sound field generated by the target source over a sphere in real-time. A spherical array sets up a boundary between the target source and the interfering sources, such that the outgoing field on the array is only generated by the target source. The proposed method decomposes the pressure and the radial particle velocity measured by the array into spherical harmonics coefficients, and recoveries the target outgoing field based on the time-domain relationship between the decomposition coefficients and the theoretically derived spatial filter responses. Simulations show the proposed method can separate non-stationary sound fields both in free field and room environments, and over a longer duration with small errors. The proposed method could serve as a foundation for developing future time-domain spatial sound field manipulation algorithms.

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Source: https://tomesphere.com/paper/1901.05122