While trying this tone generator out, I thought I had a ridiculous notch in my hearing at 532Hz, because the perceived volume dropped to about 10-20% of the neighbouring frequencies. But then I moved my head slightly to the side, and the normal volume was restored!
Turns out that I had inadvertently replicated a classic high-school "constructive/destructive interference" demonstration. Driving the pair of speakers on my desk at that frequency put the position of my head in one of the destructive-interference "nulls" where the effective volume approaches zero.
So if anyone else is playing around with it, be sure to use headphones instead of stereo speakers!
Turns out that I had inadvertently replicated a classic high-school "constructive/destructive interference" demonstration. Driving the pair of speakers on my desk at that frequency put the position of my head in one of the destructive-interference "nulls" where the effective volume approaches zero.
So if anyone else is playing around with it, be sure to use headphones instead of stereo speakers!