No voices, alarms etc??
 

When I issue orders I dont hear the crew say yes sir etc and when I sunk a few ships I didnt hear any cheers or confirmation of the hits either, is it meant to be like this??

i think its just another thing they ran out of time for. again, time to dial 1800-modder.

Sometimes my crew go totally mute. No speech, confirmation of orders etc.
A reload clears the problem.
Intermittent bug I think.

Another possibility could be your sound settings. SH5 doesn't seem to like my 5.1 surround setup: I could hear the engines and sea, but no speech. Changing to 2 speaker stereo solved it for me.