Gary Hoffman wrote:
> Has not a thing to do with your ability to hear, say, a 30 Hz tone. The
> thrummm that you hear, while I never measured it, is at a much higher
> frequency than that....perhaps a couple hundred Hz or so. But it Varies
> very slowly in amplitude over time - that is, at the beat frequency.
With equal amplitudes we have:
COS (x) + COS (y) = 2 * COS ((x + y) / 2) * COS ((x - y) / 2)
Example:
freq 1 = 800.10 Hz
freq 2 = 800.00 Hz
what one hears is an 800.05 Hz tone with its amplitude
varying from zero to twice the single tone amplitude (+6 dB)
at a rate of 0.05 Hz, which means that peaks (or throughs)
are separated in time by 10 seconds (once per 0.05 Hz half-period).
This a well known physical phenomenon, not related to hearing at all.
The resolution depends mainly on source stability and one's patience.
73,
Sinisa YT1NT, VE3EA
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