That is two channels out of phase with each other.
I think I only see one channel, how can one channel be out of phase?
Well I acquired a used sonic studios preamp to use with my sonic mics and during testing of the preamp on playback I noticed that when i got close to my front door there was hum or feedback every time I got close to that door or also a window..... strange so when I saw the weird looking waveform I wondered if that was a give away to what the real problem is with this hum or feedback?
House wiring forming a radio transmitter near the walls and doors?