Not just any sound machine, these are machines about the size of 2 paperback books that are located in toilet stalls – ok, there, I said it. And they make a sound like the sound of a toilet flushing. Now, why in the world do you need a machine that makes that sound in a toilet stall ? Well you may ask. The machines are there to provide another level of privacy for those most private of functions – a curtain of sound! Sometimes they have a button to push, and a row of small LEDs to track the progress of the sound experience. But the other night the machine was electronically wired to the commode and started automatically when the patron sat down, and began tapering off when the patron arose again. Pretty nifty way to deal with a densely-packed small-personal-space-envelop but we-all-crave-privacy society, ne?