| Thanks to all those who helped answer my questions about the diffuse sound field. Unfortunately, I no longer work in a university setting, and there is no acoustics laboratory near by, so I had to improvise...and I have to say, I came up with the PERFECT solution for a diffuse field reverberant enclosure... I stopped by a local shipping container rental contractor a few miles up the road and found two dozen 10x12x40 heavy-duty contractors shipping containers. The one I chose had 1/8" thick corrugated metal sides (which I think would not be good for high frequency propagation), but I ran an extension cord out to the box, unloaded the manikin, amplifier, speaker and computer and started testing the microphone response 360 degrees in 30 degree increments in the horizontal plane. The analysis of the frequency response show graphs overlaped almost perfectly on top of one another at all horizontal angles of manikin rotation. I found less than +/-1dB variation (response smoothed with 1/3 octave res) between 30 Hz and 12 KHz. RT 60 is still being looked at, but it is very long at a wide range of frequencies. I am also calculating DI, but I assume that the container makes a very effective acoustic reverberation chamber. I am reporting my results for the benefit of someone else that may need access to a simple, inexpensive, yet effective reverberant chamber. Phil Mc C.an.dless |