I likewise just started experiencing this same exact issue. Have had my SD for about three months, without issue. Admittedly, I had not used the speakers all that often, but up until a week ago or so, they worked just fine. The faulty situation is now happening consistently. My SD is attached to a Mac Studio, so everything is new.
SYMPTOMS
- sound from speakers cuts out after 2 seconds
- microphone input is pretty much non-functional - FaceTime users can't hear me, or hear a repeating sound
TROUBLESHOOTING (running latest OS 12.5 Monterey)
- power-cycled computer - both speaker and mic issues persist
- set up a new, totally clean Test User - both issues still present
- disconnected all peripherals - both issues persist in both original and Test User
- tested microphone input at System Prefs Sound panel in both Users - rarely reacts or reacts and then is "stuck" or "repeats"
- AirPods work correctly in both Users (AirPods use Bluetooth, so I expected this to work)
I did not associate this with a specific software update, but it could have happened from 12.3 to 12.4? Issue was definitely present for me in 12.4 earlier today. I then updated to 12.5 but have the same symptoms.
Sure feels like either a straight hardware issue, or perhaps a sw/hw combo problem. Will try to take my SD to Apple Store and have them plug in to test. Will report back after my visit. Really hope I don't have to do a clean install of OS .... ugh