If I add a 30 or 60hz tone it doesn't eliminate (not reduces) the effect,
probably because it's still too low to "fill the gap". However a 200hz tone
totally does reduce the effect.
(I say around 200hz, but I added a harmonic of the ones in the upper range,
so the period/pitch still stays the same, definitely another point for the
ear compression theory)
From: Brian Clevinger
Sent: Thursday, December 06, 2012 1:59 PM
To: A discussion list for music-related DSP
Subject: Re: [music-dsp] Ghost tone
I find it extremely unpleasant under headphones, kind of a dizzy
nausea-inducing sensation. In speakers not so much, I assume it's because
the room resonances fill in the spaces of the pulse train. I get a similar
sensation in response to some insect sounds. Maybe it's a biological
response to having a bug fly in your ear:-)
This is way beyond my scope of knowledge, but your compression idea
certainly describes the feeling. Like the brain/ear is constantly try to
adapt somehow to the periodic presence/absence of sound pressure.
If you add some energy at 30Hz or 60Hz I would think it would eliminate the
effect, since the low frequencies would fill in the "holes" between the
pulses.
I tried something similar once. If the frequency range of the harmonics
isn't too high the pulse is audible, but it's not nearly so unpleasant, more
like a tickle. It's especially when there are only high frequencies that it
gets painful.
Just goes to show how important phase is!
Brian
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