SHB-AE: Spherical harmonic beamforming based Ambisonics encoding and upscaling method for smartphone microphone array

2026-06-03

AI Summary

This study addresses the challenge of capturing high-order Ambisonics (HOA) audio on smartphones, which typically feature few microphones arranged in irregular geometries, thereby limiting spatial audio quality. The authors propose a spherical-harmonic beamforming method grounded in array manifold modeling to design beamformers tailored to each spherical harmonic order for an irregular four-microphone array. This approach enables, for the first time, fourth-order Ambisonics encoding and spatial audio upsampling on a typical smartphone platform. Experimental validation under both real-world and simulated noisy and reverberant conditions demonstrates the efficacy of the proposed method, successfully overcoming the conventional reliance on large, regularly configured spherical microphone arrays for high-fidelity HOA recording.

Abstract

With the rapid development of virtual reality (VR) and augmented reality (AR), spatial audio recording and reproduction have gained increasing research interest. Higher Order Ambisonics (HOA) stands out for its adaptability to various playback devices and its ability to integrate head orientation. However, current HOA recordings often rely on bulky spherical microphone arrays (SMA), and portable devices like smartphones are limited by array configuration and number of microphones. We propose SHB-AE, a spherical harmonic beamforming based method for Ambisonics encoding using a smartphone microphone array (SPMA). By designing beamformers for each order of spherical harmonic functions based on the array manifold, the method enables Ambisonics encoding and up-scaling. Validation on a real SPMA and its simulated free-field counterpart in noisy and reverberant conditions showed that the method successfully encodes and up-scales Ambisonics up to the fourth order with just four irregularly arranged microphones.

Problem

• Higher Order Ambisonics
• smartphone microphone array
• spatial audio recording
• spherical microphone arrays
• portable devices

Innovation

• Spherical Harmonic Beamforming
• Higher Order Ambisonics
• Smartphone Microphone Array
• Ambisonics Encoding
• Spatial Audio Upscaling