Acoustic Beamforming using a Sipeed R6+1 Microphone Array

The Sipeed R6+1 microphone array can be used for sound source localization and beamforming by combining with Sipeed Maix Dock/Go/Bit.
We calculated the pattern of this microphone array.

Sipeed R6+1 Microphone Array

The Sipeed R6+1 microphone array is a board with 7 MEMS microphones and 12 RGB LEDs.
Six microphones form a circular array with a radius of 40 mm, and a center microphone is also installed.

Sipeed Maix Bit

The Maix Bit is a low-cost development board from Sipeed, featuring the Kendryte K210 from Canaan.
The Kendryte K210 is an SoC that includes:

Dual-core 64-bit RISC-V,
KPU (Knowledge Processing Unit),
APU (Audio Processing Unit),
FFT (Fast Fourier Transform) accelerator,
etc.

The main functions of the APU are audio input of up to 8 channels and beamforming for sound sources in up to 16 directions.
According to the research of kendryte-standalone-sdk, beamforming of the APU is a delay-and-sum (DAS) method.

The image below shows the result of calculating the horizontal pattern of the substrate by DAS beamforming.

MaixPy

In the MIC_ARRAY library of MaixPy, there is a function called get_map that performs sound source localization using the Sipeed R6+1 microphone array.
This function outputs the sound level in the 8 x 8 direction, and it is unknown whether it uses the APU’s DAS beamforming.

The featured image shows the result of calculating the pattern in the normal direction of the substrate at a frequency of 4 kHz by DAS beamforming.