Damping the 59Hz standing wave?

[StuffHappens]

When the AC runs, either bedroom AC or main unit a pronounced Standing Wave peaking at 59Hz is heard throughout the camper but it peaks in the bedroom right at the head of the bed at about 77dB. It is loud enough that my wife cannot sleep when the AC runs. She doesn't do well with earplugs and earplugs have trouble blocking low-frequency noise.

Bose noise canceling headphones wipe it out but can't be comfortably worn when sleeping.

I've researched bass traps but there's really not enough room in the bedroom to construct bass traps for that low a frequency.

Does anyone else struggle with the the low frequency throb from the AC in their bedroom?

 

[trailrydr]

Thats funny... my wife actually turns on our AC fan on manual to drown out CG, highway, train and plane noises while sleeping at night.

I remember reading somewhere about the use of white noise to cancel out other sounds... maybe worth looking into that. From the net:

"Using White Noise Machines - White noise machines emit a consistent, soothing sound that can mask low frequency noise."

 

[StuffHappens]

It might be the length or attachment of some structure in the roof that is creating the resonance. There is a sharp spike at that frequency.

The AC fan creates plenty of white noise... it's the specific low frequency thrumming that is 6dB louder than the other frequencies that causes the issue. The 295RL doesn't have a bedroom slide out so it's quite small and doesn't have room for bass traps.

 

[DougW9876]

It could be the AC is screwed down too tight to the roof. Pull the cover off inside the RV and look for the 4 screws in the corners that hold it down. Loosen them up a bit and see if that helps dampen the noise. There is a point where it can be too loose, but it shouldn’t be super tight either. You might even consider adding a foam weatherstrip between the AC and the roof of the Rv to add some dampening.