Changing Inharmonicity

[Kent Swafford]

Hi Don,

I think Robert has a good question.

We know that a piano might show lower inharmonicity in high humidity _if_
that humidity has made the tuning go sharp and readings are taken on the
strings while they are still sharp.

However, stored tunings are recalled every day from ETDs and used to tune
pianos. These stored tunings work well -- don't they?

Do you have stored tunings that once worked well on a given piano but no
longer work well?

The PTG tuning exam procedure uses a stored tuning as a reference and I have
never heard of a reference tuning working well in one season but poorly in
another...


Kent Swafford


On 10/29/01 7:57 PM, "Don" <drpt@sk.sympatico.ca> wrote:

> Hi Robert,
> 
> I am basing this on years of data I collected on pianos from FAC measurements.
> 
> At 07:20 PM 10/29/01 -0500, you wrote:
>> Don Rose writes:
>> 
>>> Unfortunately inharmonicity does change with humidity levels. It makes a
>>> significant difference on a SAT or RCT. The verituner would be even more
>>> likely to show deviations as it does so much more measuring.
>> 
>> I don't believe this has ever been demonstrated conclusively.  Are you
>> sure that most of the so-called inharmonicity variation is not due
>> to measurement error?  To see what I mean, get five techs together at
>> the same time and let them each measure the inharmonicity of several
>> strings on one piano.  Let them use the same equipment, but don't let
>> them watch each other as the measurements are taken.  Then compare
>> notes.  The variations that you get in that experiment are not due to
>> anything changing on the piano, but rather to the measurement process
>> itself.  Once that level of variation has been established, you can
>> then go on to make measurements under different humidity conditions.
>> If the variation you get is substantially greater than the baseline
>> variation from the first experiment, then you will have proven
>> something.  Until then it is just speculation.
>> 
>> -Robert Scott
>>  Detroit-Windsor Chapter