On Wed, 17 Dec 2003, Michael Thames wrote:
> I said that if you increase the soundhole opening you lower the resonate
> air space frequency.
I don't understand this. If the enclosed air space had a resonant
frequency, wouldn't the lute "boom" (ie, be much louder) at that
frequency?
Herb,
Yes exactly so, this is what is commonly called a wolfe note, one note
that usually is louder and has less sustain than other notes, at least on
plucked instruments, where you can't sustain the note as on a violin etc.
When, the air space frequency combines with the plate tuning you will
get one frequency. This again is called mode coupling.
Different luthiers have there own theories, and methods regarding
matching plate tunings with air resonance tunings.
From my experience the wolfe note on my guitars is usually the same note
as what the soundborard is tuned to, and it makes it worse if the air
resonate frequency is a match to the lowest mode of the the soundborad.
This modal coupling is what happens to a beer bottle once you blow the
correct force of air in. You will notice that once the air space frequency
is activated,close to the plate frequency (beer bottle) the whole thing
vibrates at one note, contrary to what the physicist professor Bob says, as
anyone can feel the bottle clearly vibrating and this is called modal
coupling.
This is also demonstrated when a singer sings a note and the glass
breaks. The note the singer sings is the same note as what the glass is
tuned to causing it to vibrate and break.
However, Beer bottles is a bad comparison to the acoustics of how a guitar
or lute works, as the air is forced in to activate a certain pitch.
On a lute or guitar the plucked energy of the strings causes the
soundborad to vibrate and act as a filter to let through certain overtones
to create what we recognize as a classical guitar or lute.
These series of overtones are the only thing that make a lute sound
different from a clarinet, as the fundamental sounds the same on a clarinet
and the lute.
Michael Thames
Luther
www.ThamesClassicalGuitars.com
Site design by Natalina Calia-Thames
----- Original Message -----
From: "Herbert Ward" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, December 17, 2003 1:43 PM
Subject: Re: calling Dr. Helmholtz...
>
> On Wed, 17 Dec 2003, Michael Thames wrote:
> > I said that if you increase the soundhole opening you lower the resonate
> > air space frequency.
>
> I don't understand this. If the enclosed air space had a resonant
> frequency, wouldn't the lute "boom" (ie, be much louder) at that
> frequency?
>
>
