Hello,
my Respeaker 4 mic hat does not have such noise. But I have met the same problem on my ipad when I charge it with the unstable power supply in my school library. So I guess maybe there is some problem with your power supply. Could you please switch another one and try to see if there is still a noise?
Please tell me what final results do you need, maybe I can tell you which variable to modify.
Sometimes there is an awkward silence in the forum, so pls send emails to seeed directly when you need a quick response.