Feedback Wave WARNING - this starts out quiet but gets LOUD in parts. I "played" this wave music by controlling the feedback loop with the volume and EQ controls on my mixer. The sound was recorded using Amadeus Pro set to "playthrough" causeing the loop. The wave was created by videotaping the oscilloscope. I brought up the contrast in Adobe Affter Effects. New iMac Built-in Microphone It's almost invisible.