John Fields wrote:

> On Fri, 06 Jul 2007 19:04:00 -0000, Jim Kelley <jwkelley@uci.edu>
> wrote:

> In your example, with 300Hz and 400Hz as the carriers, the sidebands
> would be located at:
>
> f3 = f1 + f2 = 300Hz + 400Hz = 700Hz
>
> and
>
> f4 = f2 - f1 = 400Hz - 300Hz = 100Hz
>
>
> both of which are clearly within the range of frequencies to which
> the human ear responds.

Indeed. We would hear f3 and f4 if they were in fact there.

> Your use of the term "beat frequency" is confusing since it's
> usually used to describe the products of heterodyning, not the
> audible warble caused by the vector addition of signals close to
> unison.

The term is commonly used in describing the results of interference in
time, as well as for mixing.

> Since the response of the ear is non-linear in amplitude it has no
> choice _but_ to be a mixer and create sidebands.

Perhaps you're confusing log(sin(a)+sin(b)) with
log(sin(a))+log(sin(b)).

If you don't mind me asking, where did you get this notion about the
ears creating sidebands?

jk