Resonance between floor and ceiling... and I rent :(

Hi, I wasn't really sure whether this should go in the Acoustics forum or the Construction forum, so sorry if I'm in the wrong place. I searched around but I wasn't able to find as much info as I would have liked. Basically my problem is this: I have a resonance at around 138Hz in my room. I believe it's between my floor and ceiling; for a couple reasons. One, when I move my head up and down (OK that sounds BAD) the resonance changes, it's not as loud when I'm standing up as it is sitting in the mix position. Two, when I turn my head sideways (one ear pointed at the ceiling, the other pointed at the floor), I can hear the phase difference between my two ears. In one ear the tone will be loud, in the other ear it is soft, and this will change, again, as I move my head up and down (sigh..). Ceiling height is approx. 99 inches. Tile floor and drywall ceiling. Anyway, I know how to fix this in theory. I need a "cloud". The problem I have though, is that I rent... so I can't really do much to the ceiling. Is there a way to mount panels on the ceiling safely without destroying it or doing anything that would piss of my landlord? If so, how? Thanks.

With an 8' ceiling you should have a first harmonic at 137.5hz :D well done! you will also have them at the other dimensions of your room. maybe you could build a cloud and support it from the floor with posts. cheers john

a hah! and I got that frequency by ear with an oscilloscope! So no matter how much I treat my walls, this harmonic will still resonate, correct? The only way to fix this is by putting insulation between the floor and the ceiling? Thanks.

You might consider building some 2' x 8' panel resonators - ballpark would be 1/4" plywood over 2.5" air gap, leave the 1/2" closest to the front plywood panel as a gap (cleats and hardware cloth can help this) Since that frequency is a second harmonic, the panels would need to be placed horizontally against the walls at either 2' or 6' centered (panel resonators are PRESSURE devices, so need to be at high pressure nodes) Also, mount the front panels using flexible rubber and SCREWS with washers (finish washers look better) so you can TUNE them - this is NOT an exact science, too many material variables... Steve