Beamforming feature of the ReSpeaker Mic Array

Hi, I’m using ReSpeaker USB Mic Array for a academic research related to detecting mechanical noise.
About the featrue of beamforming in ReSpeaker USB Mic Array, could you plz tell me which type of the beamforming the ReSpeaker array is using ?
I just need to know the algorithm name ,such like "Delay and sum"or “MVDR”…etc, to classify different methods used by different devices, so don’t worry about revealing the details to me.