Subject: acoustic coupling -- help!1

Greetings,
>i too am very curious if the organ-pipe coupling phenomenon, which i think
>ed foote gave a particular name to, is solidly confirmable . . . ed?

Umm, I don't know about how "solid" the confirmation will be, but I have
spoken with two organ tuners that both worked to the same problems. Placing
two pipes of like pitch near each other will allow them to influence the
pitch of the other. They called it "drawing" and explained it was due to the
mechanical coupling of the the air. When the pitch of one grew near the
other, I was told that the beats disappeared, but when the two pipes were
measured individually, their pitches were not exact.
I know that this can happen between the individual strings of a piano
unison, because I tune with the Weinreich effect in mind and have measured
and heard it to be true. I don't get allowed around many organs, though...
Regards,
Ed Foote RPT
Nashville, Tn.

--- In tuning@y..., a440a@a... wrote:
> I tune with the Weinreich effect in mind and have measured
> and heard it to be true.

can you please describe the weinreich effect and your measurements?

thanks!

In a message dated 10/31/02 5:06:05 AM Central Standard Time, a440a@aol.com
writes:

> . Placing two pipes of like pitch near each other will allow them to
> influence the
> pitch of the other. They called it "drawing" and explained it was due to
> the
> mechanical coupling of the the air. When the pitch of one grew near the
> other, I was told that the beats disappeared, but when the two pipes were
> measured individually, their pitches were not exact.
>
> Ed Foote RPT
>
The sme effec is created when the C-C# pipe arrangement is used so that major
3rds are on the same side. The two notes tuned to 12-ET pull together to
lower the interval value close to the theoretical just 3rd of 386 cents, but
not completely. Evidently the C note rises slightly in pitch, and the E
lowers slightly in pitch.

Pauline

In a message dated 10/31/02 5:06:05 AM Central Standard Time, a440a@aol.com
writes:

> . Placing two pipes of like pitch near each other will allow them to
> influence the
> pitch of the other. They called it "drawing" and explained it was due to
> the
> mechanical coupling of the the air. When the pitch of one grew near the
> other, I was told that the beats disappeared, but when the two pipes were
> measured individually, their pitches were not exact.
>
> Ed Foote RPT
>
The sme effec is created when the C-C# pipe arrangement is used so that major
3rds are on the same side. The two notes tuned to 12-ET pull together to
lower the interval value close to the theoretical just 3rd of 386 cents, but
not completely. Evidently the C note rises slightly in pitch, and the E
lowers slightly in pitch.

Pauline

>I know that this can happen between the individual strings of
>a piano unison, because I tune with the Weinreich effect in mind
>and have measured and heard it to be true. I don't get allowed
>around many organs, though...

Ed, and All;

On a loosely-related topic, sometimes a single string develops
what are called false beats -- a deformation in the metal
moves a node or some such, and the string by itself will beat.
Sometimes, this can be completely tuned out by changing the
tuning of another unison string in the group. I wouldn't have
believed it if I hadn't heard it several times. Any guess as
to how it works??

-Carl

--- In tuning@y..., "Carl Lumma" <clumma@y...> wrote:
> >I know that this can happen between the individual strings of
> >a piano unison, because I tune with the Weinreich effect in mind
> >and have measured and heard it to be true. I don't get allowed
> >around many organs, though...
>
> Ed, and All;
>
> On a loosely-related topic, sometimes a single string develops
> what are called false beats -- a deformation in the metal
> moves a node or some such, and the string by itself will beat.
> Sometimes, this can be completely tuned out by changing the
> tuning of another unison string in the group. I wouldn't have
> believed it if I hadn't heard it several times. Any guess as
> to how it works??
>
> -Carl

must be related to this effect. the string beating by itself is a
very simple consequence of classical mechanics -- since the string is
free to vibrate in two independent dimensions, any anisotropy in
these dimensions will lead to two independent frequencies,
corresponding to the eigenvectors of the system. so i suppose if the
weinreich effect can pull different string's frequencies together, it
can certainly act on both of the string's eigenvectors, assuming the
coupling (however it works) is effective in both dimensions . . .