Wiktionary
sing out
vb. 1 To cry out in pain. 2 (context nautical English) To call out.
Usage examples of "sing out".
The harmonies weren't bad either, Robinton decided, though he didn't sing out as he would have done back in the Hall.
But he would hear himself, and sing out what had been held inside for far, far too long.
I'm behind you, and if you run a step or sing out fer help, Fll dig this fine dagger into yer backside.