I had never heard of this but discovered I was suffering from it while listening to sine wave bass tones through my speakers. I think was 80Hz. At first I thought I heard distortion and figured it was my speakers having a problem. Then I tried listening on headphones on a completely different system and still heard it, which made me think it must be something wrong with the file I was playing. Finally I listened to it one ear at a time with the headphones. The tone sounded like a different pitch depending on which ear I used! With both ears combined I got the impression of some kind of noise in the signal. Fortunately it was a temporary condition and I recovered from it by the following morning. Interestingly, the music I was listening to still all sounded in tune. My left ear was perceiving the correct pitch and with both ears combined it was dominating my perception. With the addition of the right ear I perceived noise in the signal.