When I first went to sea many of the ships I sailed on were old, built in the 1950s just after WW2. They were all fitted with sound powered emergency phones as a back up system - they work with no electricity or battery - positioned at all important locations. This technology according to wiki came in around 1944 so it is likely that sound tubes as a back up were still in use during most of WW2.
The whistle obviously attracts attention to the tube, but whether you could blow a blast down to operate the whistle from the other end I don't know. The whistle shown does not seem to have a mouthpiece. I'm also not sure how far the tubes could operate. It may have been fine for say Bridge to Captain's cabin but I doubt it would have worked to the engine room half a ship away. I would guess that, in this example, the Bridge could operate something - a bellows perhaps - that sounded the whistle in the Captain's cabin to call him to the Bridge or to alert him to converse on the tube.
Incidentally it is reported that during the attack on the USS Cole in 2000 with all power lost and communications down the sound powered telephone system remained the only working comm system.
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