[dglang]

If he was also using an Oxygen concentrator along with the CPAP machine, the sound of a quiet stealth helicopter would indeed be drowned out. No one in the room with both of those machines running would be aroused by external noises unless those external noises were very loud and UNUSUAL.

On a mission trip to Jamaica a few years ago, I slept in a house without windows. There were dogs running loose and barking all night long and someone somewhere had a ghettobox blasting dance music. About the time we started getting accustomed to the noise, the roosters began crowing.

If it was common to hear gunfire from the nearby military training facilities, even the sound of gunfire in the yard would not be considered uncommon and it would not wake him up.

I personally use a CPAP machine AND an oxygen concentrator at night. The sound of the oxygen concenrtator is loud enough that I keep it in another room as far away from the bedroom as I can get it. In our old house, I kept it out on the back porch. As the oxygen concentrators get old and worn, they get even noisier.

The basic function of an oxygen concentrator is to compress the air into different strata, siphon off the oxygen, periodically release the compressed gases remaining and then repeat the entire process over again about every 20 to 30 seconds.

There is a very audible sound of the compressor running and an audible pop as the compresses air is released into the atmosphere to begin the next compression cycle.

[TYVets]

Toward the end of her life my mother used a oxygen concentrator and as you said they do make a lot of noise. In her case the concentrator was isolated as far as possible from her with 2 closed doors between them.

The Navy SEA Ls will not talk about what is the truth and what is disinformation from the 0bama administration. In all likely hood we may never know if Bin Laden was awakened before or when his bed room was entered by the SEALs.

Thanks for your comment it does add insight that no one else has provided on this thread.