"Rich Grise" <rich@example.net> wrote in message
news:pan.2007.07.12.17.28.11.148983@example.net...
> On Wed, 11 Jul 2007 22:52:17 -0700, Jeff Liebermann wrote:
>
>> "NotMe" <me@privacy.net> hath wroth:
>>
>> (Please learn to trim quotations)
>>
>>>Actually the human ear can detect a beat note down to a few cycles.

If you are talking about the beat between two close
audio frequencies then one can easily hear a beat way
below 1 Hz.

>>
>> No, you cannot. Figure on 20Hz to 20KHz for human hearing:
>> <http://hypertextbook.com/facts/2003/ChrisDAmbrose.shtml>
>>
>> What happens when you zero beat something is that your brain is filling
>> in
>> the missing frequencies. As you tune across the frequency, and the beat
>> note goes down in frequency, most people overshoot to the other side, and
>> then compensate by splitting the different.

If you are talking about beat frequency heard when
tuning to a carrier with a radio with a BFO or in SSB mode
then one can't hear any beat below 50 Hz or so.
The audio section of the receiver blocks anything
below about 50 Hz.

>
> No, you've got it all wrong. The beat note happens because, when the
> signals are close to 180 degrees out of phase, they cancel out such that
> there is, in fact, no sound. This is what your ear detects. Now, if
> you're zero-beating, say, 400 Hz against 401 Hz, I don't know if the
> 801 Hz component is audible or if it's even really there, but
> mathematically, it kinda has to, doesn't it?

Are you talking radios or guitars?
With a guitar you might beat 400 Hz against 401 Hz.
With a radio you'd more likely beat 455 kHz against
455.001 kHz.

>
> Thanks,
> Rich
>