Re: Temperature

From: markm@naropa.edu
Date: Thu Dec 13 2001 - 14:46:34 PST


Well, I live at 5500 ft. where the air is pretty thin and dry and it
sometimes gets cold in my house. And I've played a variety of
instruments by different makers of varying quality. But I've
noticed that by far the most important variable is the quantity (in
proportion to quality) of practice time I've been putting in lately.
What a difference that makes... intonation, sound, repertoire...
you name it, I've noticed that it's much better when I practice.
Amazing... ;-)

Mark M

On Thu, 13 Dec 2001 12:40:42 -0500 Dan Gutwein wrote:

> I remember from my days as a traveling musician playing
saxophone and
> "metal" flute on the road, that when the instruments were cold
they would
> play flat. As they warmed up they would go sharper and
sharper. Since
> different musicians instruments swell at different rates, the
ensemble
> would have a hell of a time playing in tune during the
temperature
> transition. That was because the metal had contracted due to
the
> cold and
> therefore the bores were larger. When the instruments
warmed up, the
> metal
> expanded, thus reducing the bore size and the pitch
increased--not
> because
> warm air increases pitch but because the bore was smaller. I
don't
> have my
> acoustics books here at home with me, and I'm not a physics
of sound
> specialist, but I'm quite sure that the speed of sound (how fast
the
> waves
> are propagated through the air) and pitch (the wave-lengths)
are not
> related. I'm also sure that the speed of sound decreases
when propagated
> through moist warm air (like on a lazy summer day) and
speeds up when
> propagated through dry cold air. Try this for an experiment.
Sing a
> long
> held tone inside your house at indoor temperature and note
the pitch,
> then
> continue singing and immediately go outside on a cold day
when the
> weather
> is close to freezing and the air is dry and note the pitch. The
sound
> travels faster through the cold dry air (that is why walking on
snow
> sounds
> so crisp on frigid days), so the sound should seem as if it is
> clearer and
> psychoacoustically louder, but the pitch should stay exactly the
> same. If
> wave-length (pitch) and wave-speed (speed of sound) were
related you
> would
> notice a pitch difference in the cold air. This has nothing to do
> with the
> fact that warm air from your lungs is propagating the sound,
since your
> voice will be heard all over the neighborhood as a result of
cold air
> propagating the waves. If you cannot hold a steady pitch, use
a boom-box
> or a tuning fork for the test.
>
> At 11:31 PM 12/12/2001 +0900, you wrote:
> >Paul,
> >
> > >Perhaps
> > > this a question which the more physics and acoustics
literate folk out
> > > there can shed more light on.
> >
> >
>
>http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.htm
l?tc=40&tf=&v=&vc
> >=&vm=
> >
> >gives the relationship of temperature and speed of sound.
You need java
> >enabled. Enter the Centigrade number and then tab to get
the other
> values.
> >
> >At 10 degrees C (50F) the speed of sound is 337.5 m/s. At
30C (86F) it's
> >349.7 m/s--an increase of 3.6 %. The speed of sound is
directly
> related to
> >pitch and any percentage change in speed of sound equals
the same
> percentage
> >change in pitch. 3.6% is a little over a half note difference.
> >
> >Nelson Zink
>

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