Air and land vehicles are clearly audible while diving and it is also quite easy to tell the direction that they are coming from.
In real diving it is generally not possible to hear noises that are being created above the water especially if the noise creator is not physically in the water.
Play the SCUBA showcase and note the sound of the helicopter patrolling above water or in the editor place yourself as a diver and then add some patrolling air or land vehicles near to where your unit is underwater.
I have been scuba diving for several years.
Totally agree. I haven't got a chance to go SCUBA, but from snorkel depths (1-3m) it's very hard to determine sound direction.
Mass closing ancient tickets with no activity for > 12 months; assume fixed or too trivial.
If this issue is still relevant in current dev build, please re-post.