Finally, thank you very much for this, got this working now on RPi 4;
Distributor ID: Debian
Description: Debian GNU/Linux 12 (bookworm)
Release: 12
Codename: bookworm
My testing code;
arecord -D plughw:1,0 -f S16_LE -r 16000 -c 2 -d 5 test.wav