I asked a an engineer a similar question when I was working on setting up a sound system for a gym. Our concern was canceling out the echoes. His response was that theoretically you can cancel out sound with the reverse wave length of the same sound. In practice you would need one of three things to happen. 1. You would need to mic the sound at it's source and place the speakers at the same location. 2. You would need mic the location of the ears and place the speakers at the same location. or 3. You would have to have a limitless number of mics to pick up all of the sound waves bouncing off of all of the surfaces for the speakers to conceal out the sounds. The only one that is somewhat practical is number one. Say if you had an extremely load air conditioner or something and wanted to cancel out it's noise. Number two would require some sort of headphone contraption connected to a battery source and a portable/wearable PC. As far a Linux being able to accomplish the first idea I don't know. Doug _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list