Full-Digital Microphone Meta-Arrays for Consumer Electronics

Microphone arrays of various sizes and shapes are widely employed in consumer electronics devices such as smart speakers, speakerphones, smart TVs, smartphones, PCs, and headphones. Therefore, the possibility of creating arrays of arrays (i.e., meta-arrays), by easily connecting several smaller units, is particularly interesting: it allows for different shapes, with an increased number of microphones and improved performance, while keeping costs low. In this paper, full-digital microphone meta-arrays are presented: they are constituted by an arrangement of several triangular units, each featuring four digital Micro Electro-Mechanical Systems (MEMS) capsules connected in daisy-chain through the Automotive Audio Bus (A $^{\mathrm{ 2}}\text{B}$ ). Two prototypes have been built: a planar meta-array made of seven triangles (28 capsules) and a 3-dimensional meta-array with 14 triangles (56 capsules). Numerical simulations were carried out and compared against experimental measurements performed on the prototypes, showing an excellent matching. Finally, the 3-dimensional meta-array was compared with a spherical microphone array widely considered the state-of-the-art equipment in the last decade, demonstrating its potential in telecommunication applications.