First-order ambisonic microphones with MEMS and condenser capsules

Technologies that produce and deliver immersive VR content are still growing. Ambisonic microphones are available in various types, from the FOA (first-order ambisonics, e.g., Sennheiser AMBEO VR Mic) to HOA (up to fourth-order ambisonics, e.g., MH Acoustics Eigenmike). They are designed with different capsules, from low-cost MEMS transducers (e.g., Zylia ZM-1) to high-grade condenser capsules (e.g., NEVATON VR). Each type of microphone has different parameters, design, spatial quality, and sound quality. This paper presents two designs of a low-cost FOA microphone based on low-noise MEMS (Infineon IM69D130) and electret capsules (JLI-2590A) in an identical tetrahedral arrangement. Details of the design, fabrication, and testing of two FOA microphones, including their frequency and directivity responses and subjective audio quality evaluation compared to commercially available solutions, are presented. This study aims to indicate whether the microphone capsule's type affects the recorded sound field's quality and to what extent.