Klarinet Archive - Posting 000412.txt from 1998/09

From: "Mark Charette" <charette@-----.org>
Subj: Re: [kl] Re: Pitch standards
Date: Mon, 14 Sep 1998 02:09:39 -0400

>> Dan,
>> I'm at a loss here. If in fact a pitch standard is set at a'=440,
where
>> does temperature come into effect? It is a vibrational standard only.
>> The currently adopted _standard_ of a'=440 (in 1939) is irrespective
of
>> temperature; while the setting of an orchestra's tuning pitch may be
>> other than a'=440 for physical reasons (including that of
temperature),
>> we can only say that they are tuning to something other than the
>> standard; say, 2 Hz above or 2 Hz below the _standard_. If otherwise
(if
>> the _standard_ is allowed to vary) then there would be no such thing
as
>> a standard at all.
>>
>> You can have a pitch standard of 442 Hz, but to call it a' would be
>> incorrect. It could only be called a vibrational standard of 442 Hz
or a
>> standard vibrating 2 Hz faster than the official standard of a'=440
Hz.
>> An orchestra may call it A, may finger it as A, may huff and puff and
>> whatever - but it isn't the official a'; at least, not until a
>> contentious bunch of grumpy people decide to call a'@-----. _Then_
>> A'@-----.
>
>I think it to be a matter of physics. If something is vibrating
>as a certain speed, that same material will vibrate at a different
>speed if the temperature is changed. Thus the pitch will change.
>
>Also, I believe that the standard for pitch states a material
>of a certain nature (such as a tuning fork made of platinum or
>gold or whatever) vibrating at a certain frequency produces a
>specific pitch at a given temperature. Change the material,
>the frequency, or the temperature, and you affect the pitch.
>
>If I remember correctly, the first attempt at having a standard
>pitch was called "Stuttgart pitch" and it specified a vibration
>of 430 at a temperature of 18.6 degrees centigrated. I once
>had to look it up in Groves (which I do not have a copy of
>at home) and was surprised to see the temperature so carefully
>described.
>
>Any orchestra would complain about their ability to achieve
>a predefined pitch if the room were too cold or too hot. My
>orchestra even had it in the contract; i.e., if the temperature
>was too hot (for outdoor concerts, obviously) we did not have
>to play, it being considered dangerous for the instruments and
>the inability to achieve a specific pitch standard.

Dan,
The reference standards themselves (the physical embodiments) are
temperature correlated; i.e., they are only standards given particular
physical environments. If the environment does not meet some certain
specifications, then the "standard" does not apply. In other words, if I
have a tuning fork made which represents the standard of a'=440 at 72
degrees F., and I take it to a place that is 85 degrees F/, then it is
_no longer_ a standard. It is a tuning fork which beats at an incorrect
frequency, not the frequency of the standard it was constructed to
match.

The scalar value of a'@-----. The
physical embodiment of the standard may. You remember crystal ovens,
right? A quartz crystal, cut or grown in a particular orientation,
vibrates at a particular frequency when excited by electrons. To use
these crystals _as standards_, their temperature had to be controlled
very precisely (along with using an orientation that did not show much
temperature deviation). In another usage, the frequency difference
between a temperature stabilized crystal and one located where one
wished to measure a temperature was used to determine the temperature.

Of course, that leads us to the slippery slope of temperature and time
standards ...

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