After a specially intense workout (biking, running...), listening to music with headphones, I hear the music pitch has dropped slightly. What I find odd is that not all parts of the sound are detuned, just the low frequencies.
It happens to me every time I push the workout a bit harder than normal. I can hear the bass out of tune with the rest of the instruments. After a couple of minutes of rest, my hearing is back to normal.
What could be causing this effect?