Re: Measurement of pitch


<matt271829-news@xxxxxxxxxxx> wrote in message news:1165284021.489763.177880@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| Sorcerer wrote:
| > <matt271829-news@xxxxxxxxxxx> wrote in message news:1165278567.848132.174990@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
| > | Hi
| > |
| > | At what time in history were the range of frequencies of audible sounds
| > | first roughly known? Who made the first scientifically accurate
| > | measurement of the frequency of a sound wave, and when?
| > |
| >
| > Who knows... pipes date from 1000's of years.
| > http://www.philtulga.com/Panpipes.html
| > http://www.sciencemusings.com/blog/images/PanGod.jpg
| >
| > The first serious study (non-musical) was by Doppler.
|
| Thanks for the Doppler reference - I'll check that out. I know that
| wind or stringed musical instruments have been around for thousands of
| years, and I suppose that from the earliest times it must have been
| apparent that the sound that they made had something to do with
| vibrations. I guess my first question is really asking at what point in
| history was the order of magnitude of the frequencies first roughly
| understood (prior to exact scientific measurements). For example, when
| an ancient pipe player played the note that we now call middle C, would
| anyone have had any clue that the frequency was very roughly a couple
| of hundred hertz, rather than say, twenty hertz, or two thousand hertz?
| Or would that understanding only have come much later in history?

That would come later. Here's why.
Galileo Galilei, father of modern science, was very interested in much
simpler ideas and lower frequencies, such as the swing of an incense
burner in church.
http://www.fotosearch.com/comp/DGV/DGV636/1535085.jpg

A big one, like this:
http://www.travelbybike.com/others2/camino/q2.gif
" 8 men pull ropes attached to a pulley contraption and swing the burner
almost the entire width of the church from one end to the other almost
touching the ceiling. "

Galileo connects frequency with length, timing the swing of
the incense burner with his own pulse. The incense burner
itself is a giant pendulum. Everyone went to church and they
always forgot to bathe first, having been baptised as babies,
so incense burners helped.

But what he had no way of measuring accurately was the speed of sound.
The best he'd be able to do is count pulses on his wrist between a
lightning strike and the rumble of thunder following, and then
measuring the distance from where he was to where the lightning
struck because he didn't have a wrist watch and the old church clock
didn't have a second hand. Many older clocks didn't even have
a minute hand, just an hour hand, and it isn't easy without
a handy thunderstorm either.

Now frequency is speed of sound divided by wavelength
and there is no way even Doppler could actually COUNT
the vibrations, it has to be computed.
So even though an organ pipe had a low pitch if it was a long
and a high pitch if short, it took a mathematician and a better
clock to compute 440 Hz, although a musician could detect
whether a note was sharp or flat without a reference note
and it was known that a pipe of half length was an octave higher.
What Doppler (for whom doppler shift is named) did was
employ a couple of musicians to play a trumpet (a pipe) ,
one standing on a train while the other was at the trackside, and
have the train pass at different speeds.
The lowest 'A' on a piano is 27.5 Hz, and a good pianist
can play 30 notes a second. I can manage more by running
my finger down the keyboard, but that isn't playing the piano
and I'd be hard pushed to measure the speed of sound
without modern equipment, although I can measure the
length of a harp string or organ pipe quite easily. A good clock
is essential. The man for whom the speed of sound is best known
is Ernst Mach, and he lived until 1916.
http://library.thinkquest.org/18033/mach2.html
http://www-history.mcs.st-andrews.ac.uk/Mathematicians/Doppler.html



.

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