Can't be linked to keys, coz everytime you press it (in periscope view or not) you'll hear the sound.
Have to be linked to the movments of turning the scope (horizontally and vertically).
The pitch part might be the awkward part... the own game has a pitch controler, but I'm not 100% that will fit in this case. There's no need for two sounds, just one sound will do. The pitch controler itself will simulate the start/stop of the electric motor from the scope.
Might look into the snorkel aswell...
If gets to work, might be incorporated into SH4.
I'll take a look on it on the weekend. If I manage to pull it off, will be on the next release of the sound pack.
I'm still looking for some german speakers to help me making new voices to replace the old ones. I need 9 candidates!