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.

翻译：随着虚拟现实（VR）和增强现实（AR）技术的迅速发展，空间音频录制与回放引起了日益广泛的研究兴趣。高阶Ambisonics（HOA）因其对多种播放设备的适应性以及集成头部朝向的能力而脱颖而出。然而，当前的HOA录制通常依赖体积庞大的球型麦克风阵列（SMA），而智能手机等便携设备则受限于阵列构型和麦克风数量。我们提出SHB-AE，一种基于球谐波束形成的、利用智能手机麦克风阵列（SPMA）进行Ambisonics编码的方法。通过根据阵列流形为各阶球谐函数设计波束形成器，该方法实现了Ambisonics编码与升阶。在真实SPMA及其模拟自由场对应物上的验证表明，在噪声和混响条件下，该方法能够仅用四个非规则排列的麦克风成功编码并将Ambisonics升阶至四阶。