I was playing around while sitting on the throne. The separate throneroom in the master bathroom is about 3x6x8. I usually whistle all the time, and I noticed a resonance on one of the notes I was whistling. So I found the exact freq and listened to it ring with short whistle impulses at that freq. Interesting tone, interesting overtones, I thought, maybe those are the other room dimensions singing along. So I lowered the pitch of my whistle until I found the next largest resonance. Sure enough at an exact frequency it rang like a bell, for a good 2 seconds after the impulse. A little higher or lower pitch and it would not ring. Then I went lower to find the room height slap echo mode, easy to find, rang true. No towels or rugs in there just 6 hard walls and a toilet. I am easily entertained.