[Harp-L] Sorry, it's combs again and again

[B Boggs <ceudoazul@xxxxxxxxx>]

Noting Vern's, and others, honest research on combs, I am intrigued with the idea of the vibration of the reeds being conducted to the ear and brain through bone.
Putting an ear to a railroad track is an analogy.
The instrument is in the mouth near the ears and brain with bone and soft tissue- lined acoustic chambers (sinuses, Eustachian tubes, etc.)  with vibrations doing all kinds of cosmic things. 
Any way to measure these factors?
It would explain the conviction of differences percieved by skilled players.
Forgive me, I know this has been brought up before.
 
With respect,
BB

Date: Mon, 22 Sep 2008 18:24:51 +0200
From: Steve Baker <steve@xxxxxxxxxxxxx>
Subject: [Harp-L] Sorry, it's combs again
To: Harp-L <harp-l@xxxxxxxxxx>

Thanks Brendan for your thoughtful contribution to this discussion.  
This still seems to me to raise the question, what exactly is it that  
the player is perceiving as different? Suave Blues Man's suggestion  
to test this objectively seems to me the only way to go from here.

During my comparison of around two dozen otherwise identical combs  
with specific differences in material and finish, using identical  
covers and the same two sets of reed plates, my notes showed  
consistent differences in sound. I have no doubt that these  
differences actually exist, and even though they are relatively small  
and may not be noticeable to the listener, I notice them. I assume  
they are the result of slightly different acoustic overtone profiles,  
which will be measurable in the same way as for example the sound of  
stainless steel reeds is verifiably different from the sound of brass  
reeds, even though most listeners won't notice the difference. How or  
whether the difference is perceived and interpreted (or not) by the  
listener doesn't necessarily have any bearing on whether or not it  
actually exists.

In Vol 61/83 Ken (Mojo Red) mentioned our comparison at SPAH between  
his MB Deluxe fitted with the brass comb and my standard MBDL. Not  
surprisingly, his one was noticeably louder than the harp with the  
wooden comb, which is after all one of the reasons why people spend a  
load of money on metal combs. I presume the difference is caused by  
the fact that the acoustic conductivity of brass is higher than that  
of wood and the inner surfaces reflect sound waves more strongly,  
both of which contribute to making the instrument sound louder and  
brighter.

In order to document the effect of comb material on sound it should  
only be necessary to play the same sustained single notes with the  
same air pressure and size of air column on all test combs (using the  
same reed plates in each case) while recording the overtone profile  
and the volume. The harmonica can easily be blown/drawn mechanically,  
which ought to satisfy even the most hardened sceptics. I have  
arranged to run tests later this year in the Hohner acoustics lab to  
objectively measure any differences and will post the results here,  
so maybe we can then finally lay this subject to rest,

Steve

Steve Baker
steve@xxxxxxxxxxxxx
www.stevebaker.de
www.bluesculture.com
www.youtube.com/stevebakerbluesharp