I've a friend who served on the USS America (aircraft carrier) in the early 90's. His "rack" was in an area directly beneath the catapult system.

According to his wife, to this day, he still requires no less than two physical alarm clocks set to go off within minutes of each other at full volume to rouse him from slumber.

The lesson here is that your child will adapt to noise and become (no pun intended) "sound" sleeper.

Absence of sound may cause restlessness, so keep it cranked!

"Someone tries to kill you - you kill 'em right back!" Capt. Mal Reynolds