[CAUT] Re. Link to Young paper

[Fred Sturm]

On 1/18/07 6:00 PM, "James Ellis" <claviers at nxs.net> wrote:

> Fred Sturm makes some interesting observations.  He is correct.  These
> anomalies are not confined to bass strings, but the reasons are different.
> Most piano wire made during the past 60 years is sufficiently uniform so
> that the anomaly does not come from the wire itself, but from whatever it
> is attached to.  Terminations are bound to affect it, and the shorter the
> string, the more effect the termination will have, especially in the duplex
> sections.  Anomalies can also occur in the longer plain-wire strings when
> some resonance of the piano's bridge and soundboard reflect back into the
> string.
> 
> Sincerely, Jim Ellis
> 
> 
Hi Jim,
    You write of some resonance of the piano's bridge and soundboard
reflecting back into the string. My notion is that the soundboard assembly
includes the strings. Hence its feedback to an individual string, or,
perhaps more precisely, its effect on the measured partials that string
produces (what we hear and measure comes through the soundboard assembly)
includes the tension of the strings and their vibrational modes. Hence, I
speculate that if you tuned a piano with a low stretch and again with a high
stretch, this might affect the measured inharmonicity. If my notion is
correct, the higher stretch would produce higher inharmonicity readings. I'm
thinking there is some resonant coupling between the pitch of the strings of
the piano as a whole and the partials of the string being measured. Bigger
stretch would mean higher pitches toward the top of the piano, hence more
reinforcement toward the sharp side of the  partials.
    This is just speculation based on reading lower inharmonicity after a
piano has been tuned. What could cause that? I speculate that it is some
kind of coupling as described above.
Regards,
Fred Sturm
University of New Mexico