String coupling.

[Joe & Penny Goss]

Ron,
Me thinks that the ETD only listens to one partial while the ear can listen
to the whole sound and the tuner then finds the sweet spot where the two
sound as one then the three as one.
As for the coupling, could it be that the ETD hears the wide part of the
string vibration whilest when the two strings sound together it hears and we
hear the low? Sort of like the crest and then the bottom of a wave?
Joe Goss
----- Original Message -----
From: Ron Nossaman <RNossaman@KSCABLE.com>
To: <pianotech@ptg.org>
Sent: Tuesday, June 20, 2000 4:25 PM
Subject: Re: String coupling.


> >I would be interested in your observations using the same measurement
> >technique.
> >Regards Roger
> >Roger Jolly
>
> Alright Roger, gang, I tried it just moments ago, with the back scale
open,
> on a half dozen unisons in the killer octave. In every case, tuning each
> string of a unison as perfectly as I was able to the Tunelab display, the
> unison did indeed drop when all were sounded together, just like you said.
> Also in every case, the unison sounded rougher than I can tune it aurally.
> Touching up aurally, the unison pitch drop disappeared again, or was
> greatly reduced. Checking each string individually against the display,
> they weren't precisely the same anymore, but the unison as a whole was on
> pitch and sounded good.
>
> Why?
>
> Right or wrong, I think it's because there's no reason to assume that the
> partial structure of all three strings in a unison is identical, and they
> in fact aren't. Matching one particular partial of all three strings to a
> common pitch doesn't guarantee a "tuned" unison, because a unison most
> probably can't be "tuned" in the first place because of the partials
> mismatch. It can only be optimized at "minimum garbage". When the fifth
> partial of one string is slightly more prominent or off pitch than the
> measured partial, and the fourth partial of another is doing similar
things
> against the eighth partial of the third, the tuner aurally finds the
> subjective optimal balance, where the ETD is quite satisfied with the
> chosen partial(s) match, even if the unison stinks. This is probably
> important, but it's not the whole phenomenon, since it can sometimes be
> nullified by aurally tuning the unison. Then again, it just occurred to me
> that it could indeed prove to be the whole phenomenon, with something
> similar coming from an open duplex, front or back. It may be that you
> simply don't have control of the duplex segment pitches necessary to
> achieve the aural balance you can in the speaking segments. It might be
> just that simple, or I just don't know how to run Tunelab.
>
> I realize that this seems to be a gruesomely complicated thing, and at
this
> point I'm trying to identify and assign helmets and lockers to all the
> major players and keep the endless disconnected details in the cheap seats
> until they can be fitted into a basic premise or two, which I'm currently
> groping for. In the end, who knows? Time will tell, and the quest is
young.
> I'm still on the first piano, and we haven't even gotten to the argument
> stage yet.
>
> Later,
> Ron N
>