I tuned out of AA after a flamefest where several members, engineers in the know mind you (at least while they were online), swore that there was no need to build speakers that could play below 50hz. Apparently the physical length of the wavelengths are so long below that frequency that you would have to sit over 30 feet away to hear them. Furthermore, you can only hear something at the exact moment the wavelength is at 1 cycle or more. In addition, you imagine you hear below 50hz because you have heard it before, other places than your listening room of course, and your brain fills in all the information below 50hz from memory. Claiming to have heard below 50hz was to no avail, just your imagination. Why my imagination could hear a test tone between 10 and 49hz, and identify it without knowing before hand what was being played, was not explained.