Bob,
The initial question was what effect does the rosette have on the lute.
I said that if you increase the soundhole opening you lower the resonate
air space frequency. You know and I know this is correct, as applied to the
guitar or lute.
You then stated I had it backwards, using beer bottles and forced air
physics as your example, which again has nothing to do with how air is moved
through a sound hole of a lute or guitar.
Your just dancing around the the issue, trying to cover your
derriere(sp?), and confuse everyone because you made the initial mistake, of
saying I was the one who had it backwards.
As a college physics professor, I'm surprised to see, you don't
understand this very basic principle of acoustical science, but then again
allot of physicists I know don't have a great deal of expertise in
acoustical science either.
At this point The Doctor now is talking about flutes, which really has
nothing to do with the way a guitar or lute produces sound. Maybe someone
should tell the doctor to stop blowing into the soundhole and start plucking
the strings!
Bob, Lamberts is a bit touristy for us locals, next time your passing
through town, try the Trading Post, it's much better.
Michael Thames
Luthier
www.ThamesClassicalGuitars.com
Site design by Natalina Calia-Thames
----- Original Message -----
From: "BobClair or EkkoJennings" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Friday, December 12, 2003 8:37 AM
Subject: calling Dr. Helmholtz...
> <[EMAIL PROTECTED]> writes:
>
> > I've just spoken to my physicist friend, and he explained it like this.
> > When you have a beer bottle and blow into it, the pitch changes
according
> > to how much beer ( air volume) is in the bottle.
>
> Your physicist friend is right. And so am I. The resonance depends on both
the volume of air and the area of the opening. (The resonant frequency is
proportional to the square root of the area divided by the volume.) But
unless you intend your guitars to function as variable volume beer
reservoirs as well as instruments, the proper experimental procedure is,
alas, to refrain from drinking the beer during the experiment and vary the
opening. (I might add that nothing in Every Girl And Boy's Big Book of
Experimental Physics prevents you from sampling the contents of the other
five bottles of fine beverage in that six pack you bought just for this
purpose.)
>
>
> >I just looked this up in my book here
>
> Which book ? Where ?
>
> > One needs a fixed solid air cavity with an opening. As one increases
> > the size of the opening it lowers the air space resonance, period!that
is
> > science. Bob actually has it ass backwards!
>
> I'm not sure what to say to this other than to inquire about which
controlled substances you may have ingested recently. A beer bottle is
certainly a "fixed, solid air cavity with an opening" and as you close the
opening the frequency of the air resonance goes down.
> Science doesn't operate by shouting or by writing "period!" at the end of
a diatribe. It operates by experiment. Michael did you even bother to tear
yourself away from your computer and actually try this? Lutenetters! Help
Michael out here. Try this at home and report back. Take a wine or beer
bottle. Fill it 2/3 full with water. (The change in pitch for a given change
in area is bigger when the volume is smaller - patially filling it with
water makes the effect easier to see (hear) but if you think this makes the
results suspect leave the bottle empty). Blow across the bottle, note the
pitch. Now cover half the opening with a
> finger. Try it again (it may take a bit of practice to get the note). Did
the pitch go up or down?
>
>
> > I actually don't really get what Bob is talking about because he is not
> > using science and I have a hard time following him.
>
> May I suggest that this might be due to an insufficient background in
basic science and a slightly overwrought emotional attachment to a dearly
held, but incorrect idea? Seriously, I taught college physics for a number
of years and as most professors will tell you, every once in a while you get
the undergraduate equivalent of a "flat earther". A student will appear for
office hours and be so frustrated and attached to their way of doing things,
that they cannot see it when you point out where they have gone astray. At
some point it becomes a waste of time for both of you. My way of dealing
with it was to tell the the student "this is something you have to go home
and think about quietly by yourself for awhile."
>
> Michael, I make the same suggestion to you. Take a break. Go to Lambert's.
Have a nice dinner. Then take the wine bottle home and try the experiment.
Get a copy of the _The Fundamentals of Musical Acoustics_ (Arthur Benade).
Give it to your physicist friend along with _all_ the correspondence from
this thread (not just your side of the story). Let him read the relevant
chapters of the book and have him explain it to you. If the Taos library
doesn't have the book this link:
>
> http://www.phys.unsw.edu.au/~jw/Helmholtz.html
>
> has a nice explanation of Helmholtz resonators as well as links to other
pages on acoustics.
>
> > This really is not up for debate it is pure science, no matter how Bob
> > trys to sell it!
>
> I'm not selling anything. Regrettably I get no commissions from the
Physicist's Union. If I did I would be trying the experiment with a higher
class of beverage bottle.
>
> ........Bob
>
>
> ____________________________________________________________
> ____________________________________________________________
>
> Replies: (remove the "ZZZZ")
>
> Ekko Jennings: [EMAIL PROTECTED]
> Bob Clair: [EMAIL PROTECTED]
