I know what you mean.

When I totally lose it with the noise, and it's also seemingly coinciding with naughty behaviour, I put him on the naughty chair. Timer doesn't start until he's quiet. So I do get (eventually) 5 minutes of quiet.

One thing that I am doing with my son is teaching him some memory stuff - poetry (currently teaching him "tiger tiger" by Blake) and that's giving a bit of to/fro stuff. And also encouraging him to stop, think, speak. To actually wait a couple of seconds and not talking for no reason, ITMS?

Good luck - I feel for you.