[Harp-L] Re: Combs

["Rick Dempster" <rick.dempster@xxxxxxxxxxx>]

That's good JR.
                          I may have suggested this one before: Pick up one of those cheapo music box innards from a $2 shop, wind it up and hold it in your hand. Not very loud; now, sit it on a wooden table; MUCH louder.
                          Now, play you harp, listen, then press the back of the comb against the table, or any solid peice of wood (you may want to try it with covers removed to allow full contact. Difference? Zilch!
                         If nothing else does, this really  proves the whole 'materials' question for me
                         There is, I believe, a small amount of vibration transmitted, because if you play the harp between your lips, and then try pressing against or holding it with your teeth, the volume seems to increase, or perhaps be directed to your ears in a more internal way.

RD

>>> Jonathan Ross <jross38@xxxxxxxxxxx> 24/09/2008 10:00 >>>
Derwood Blues wrote:

"Generally we are in agreement other than the fact that you appear to  
be much
more sure of your position even though there has been little scientific
study of the comparative level of sound production from the reed and the
"sound board" (reedplates and comb) of the harmonica. "

Calling the comb and reed-plates of a harmonica a "sound board" is  
loaded with presumptions.  This is a case where the use of  
terminology presupposes an outcome--ie, that these are active agents  
in the production of the sound and thus effect it if altered.  Better  
to use the existing terms "comb" and "reed-plate" as these are truly  
neutral, easily understood and perhaps most importantly, widely used.

"While driving home today I was thinking about what a salesman did  
with my
brother in law when he bought his seagull guitar. T<snip>
material and design. Then my mind wandered to electric guitars and
resonance. And I wonder if that is a better analogy. The wood used on an
electric guitar effects the resonance of the strings. Might the comb
material have a similar effect? Again you may argue against it but  
all this
is hypothesis that is not tested."

It has been tested.  Enough to say that a listener cannot determine a  
difference due to comb materials.  That is not the same as knowing if  
there is any change whatsoever, but it is a lot more than a  
"hypothesis that is not tested".  Check the archives and read what  
was written at the time, including some very detailed statistical  
analysis of the results of both tests.  These were not perfect, but  
they were serious, significant and should not be dismissed.

But, more to the point, no this analogy isn't useful.  In a string  
instrument, the sound of the string itself is not the primary factor,  
but rather the vibrating membrane which the energy of the string is  
used to drive.  It is this vibrating body which puts air in motion,  
generating what you hear (with perhaps a minimal contribution from  
the sound of air around the string).  In a wind instrument, the sound  
is created by disrupting the flow of a moving column of air.  The  
reed (either beating or free) acts as a gate, opening and closing to  
allow the air through.  In neither beating nor free reeds is the  
vibration of the reed transfered to a flexible membrane which can  
move a body of air.  These two methods of producing sound waves in  
the air are entirely different.

People seem to assume that just because something is a musical  
instrument other instruments are germane to it.  There are virtually  
no similarities between a violin and an organ, but people would still  
expect there to be.  It's like thinking that because certain factors  
are important in making a good saw they will also be important in  
making a good CNC laser machine, because both are tools which cut  
things.



  ()()    JR "Bulldogge" Ross
()  ()
`----'



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