Sorry Petr, perhaps I misunderstood. I am talking about the FFT
spectrum of the resulting signal, after nonlinear combination. In
such a case combination tones appear in the spectrum.

Instead, I meant that FFT spectrum of a couple of pure tones (low
volume, no nonlinear interactions) is just made up of such two
tones, even if you hear a clear beating (loudness modulation) as in
the case of a guitar being tuned.

I understand this is a delicate point, I am doing also tests with
FFTs to clarify that.....

Max




--- In tuning@yahoogroups.com, "massimilianolabardi" <labardi@...>
wrote:
>
>
> > Then you are not talking about combination tones. Combination
> tones do not appear themselves in the spectrum and you don't see
> them in FFT analysis. If they, for any reason, eventually do
appear
> in the spectrum, then they are not combination tones anymore.
> >
> > Petr
> >
>
> Exactly Petr. Here is the excerpt from my post about "beating
> beats"....
>
> "Since the beatings are also heard at low volume, they can't be
due
> to combination tones. Furthermore, combination tones would produce
a
> pitch, that could not be heard at least in the case of 12-ET major
> triad, at 5 Hz or so."
>
> Max
>