I discovered something very unusual about my ear. My left ear, to be precise.
For quite some years now, I've noticed that it is more sensitive to loud noises than my right, and tires more easily. But this morning, I stumbled onto something quite bizarre. I was working on a module in Reaktor (an audio plug-in building kit from NI) and was testing some simple oscillators through separated left and right channels. I was using the headphones because my wife was still asleep.
Here's the short of it. When playing a sine wave in at middle C in my left ear, the perceived pitch dropped dramatically when it got to a certain volume. Not so loud as to be painful, mind you. It dropped almost a whole step to Bb! This does NOT happen in my right ear. This also does not happen when I use a triangle wave, at least not at the levels I was trying. It wasn't the headphones (swapped left vs. right on my head to double-check), but it didn't seem to happen in the speakers (though I haven't tried at very loud levels yet.)
I seem to recall in my acoustics class many years ago that perceived pitch should drop slightly at high db levels, but this was a dramatic drop, and in one ear only.
Anyone know anything about audiology, psychoacoustics, or related matter that might shed any light on this? I searched around the web a bit, but have so far come up with little of any interest.