Violin bridges

[Phillip L Ford]

On Sat, 05 Jan 2002 15:04:59  
 Richard Brekne wrote:

>> Actually I think that a violin bridge is more illustrative of Ron's position
>> than your own.  If the violin top is being activated by compression
>> waves then what difference would it make what the bridge looked like?
>> It could just be a solid piece.
>
>I dunno Phil... The more I read on all this the more clear the message comes
>through. No matter what else is happening, compression waves are very very much
>in the picture when ever vibration energy is exchanged from one medium to
>another

They may be in the picture.  I won't try to deny it.

>
>> The bow is moving the string side to side.
>> The top needs to move up and down to move the air so that we can hear
>> the violin.  So violin makers have cleverly devised a bridge and soundpost
>> system to convert the side to side motion of the string to up and down
>> motion of the top.
>
>Ok wait a sec... even if the string is moved side to side.... (which it is not)

Au contraire.  See http://www.speech.kth.se/qpsr/tmh/96-4-009-013.pdf

According to Mr. Eric Jansson, and I quote "the violin bridge is excited by
an impulse in parallel with the bridge and the top plate (the main direction
of string excitation)...".  You'll find this in the Theoretical Background section.
Granted there is some lesser excitation in other directions.  Let's not be
picky.

>The more I get into this "vibration and sound" thing the more evident it seems
>to me that we all need to take a closer look at just what is happening when
>something is vibrating. It seems like we are too easily caught up in vibration
>as something you can touch, see, or feel... the transverse component.

Maybe.  But as Ron N has pointed out, others seem to be caught up in the idea
that if movement is small or happens in short intervals of time it can't be
happening, which the paper referenced above, for one, doesn't seem to bear out.

>
>Conjecture is a good thing... as far as it goes. Makes you think out loud,
>bounce ideas, and hopefully stimulate one to looking deeper and deeper to find
>better answers to questions we think we know something about.  Think ON !! :)
>
>--
>Richard Brekne
>RPT, N.P.T.F.
>Bergen, Norway
>mailto:rbrekne@broadpark.no
>

I agree completely that conjecture is a good thing.  I see that as one of the good
things about these discussions.  How do you know what to try or what to investigate
unless you throw out some ideas first.  And anyone who's ever participated in a
brain storming session or think tank knows its counterproductive to suppress or
laugh at 'stupid' or 'ridiculous' ideas.  Sometimes good ideas come from someone
deliberately throwing out a seemingly silly idea to get people thinking in a different
way or from someone playing devil's advocate.   I think it's a shame that some level of
browbeating and ridiculing occur on the list.  It prevents those who might have
good ideas (but which are unproven or untested or possibly even half-baked) from
sharing them with the rest of us who might be able to make use of them.

However, in this case this is not a conjecture of mine.  This 'theory', if you prefer
to call it that, came from reading papers and books written by violin researchers.
To name a few:

Cremer, L  Physik der Geige.  Hirzel Verlag.  Stuttgart.  1981.

Research Papers in Violin Acoustics 1975 - 1993.  Carleen Hutchins editor.
Acoustical Society of America. 1996.

Muller, H A The function of the Violin Bridge.  Catgut Acoustical Society
Newsletter 31, pg 19-22.

Trott, W J The Violin and Its Bridge.  Journal of the Acoustical Society of
America 81(6).

I've also included a few other references in my reply to JD if you want to take a
look.

With all references, as with other opinions offered in this discussion or others,
you can choose to believe them or not.  When there are conflicting references
you must make a choice.  JD's reference seems to think that the shape of the
violin bridge has something to do with how long it takes sound to travel through
the bridge.  My references seem to think it has to do with something else.  I'll
choose to believe my references.  You're free to do as you please.

Phil F

PS  I've been trying to avoid getting into this discussion for weeks.  Now I've been
dragged in.  This thing is like a black hole.