[Harp-L] Re: Fatigue and Reed Life: An Objective Test?

["Brendan Power" <bren@xxxxxxxxxxxxxxxxx>]

Some considered replies to my post from Vern and Phil. Vern makes good
points about the testing process:

"IMO, the ideal test would be to connect twenty or more reedplates of
each 
material type to a pump which would sound them continuously. (What a 
cacaphony!) Maybe push them hard at 10 in. H2O pressure...about twice 
"cruising speed" pressure for the average reed. Then measure the time it

takes for half of the reeds in each group to fail. The difference in
these 
times would be a meaningful measure of the difference of the material's 
tendency to fatigue.

Separate data could be collected on reeds of the same pitch.
Any test using just a few reeds would be subject to errors arising from 
reed-to-reed variations among those of the same material. Tests using
human 
players would exceed their endurance and would introduce many spurious 
variables."

And Phil says:

"This sounds like something that would be more feasible in a Consumer
Reports type of laboratory setting than on a public stage, even at a
harmonica convention or festival. Lab tests -- with proper scientific
controls -- with every reed material subjected to identical stress tests
would reveal the complete range of experience without bias or
favoritism. At the same time -- or another time -- some kind of a
graphic sound spectrum test (mmm good) might show any relationship
between the quality of sound produced (as opposed to simple noise) and
level of reed stress/failure. 

This in turn could provide useful information about how playing
styles/air pressure could affect not only reed longevity but sound
production -- how the player can get the best sound out of a harmonica
without destroying the reeds. Now this would be news everyone could
use."

Hmmm.... Yes, but...!!! I agree this kind of test would reveal the most
precise and reliable information about reeds when activated by machine
pumps. But is that how they will work on a particular brand of harp in
real players mouths? Extreme repeated note bending is generally the
factor that causes reeds to fail.

So I suggest two tests: one in scientific lab conditions using a machine
as Vern and Phil suggest, and another test on stage as a kind of
performance with several human testers playing real harmonicas, but
subjecting certain reeds to BRUTAL bending pressure. This would ignore
reedplate thickness and actually test real harps in real mouths.

It's well known that some players bend so hard that they go through
several harps in one show. I was once at the Hohner depot in Virginia
and they were stocking a box of Special 20's for John Popper, with lots
of extra D harps. They said he goes through a few D harps in a show and
simply tosses the dud ones out to the audience! The 4 draw reed on a D
harp is often cited on Harp-L as prone to early failure.

If a player bends a reed down repeatedly to its absolute maximum (ie.
well flat), it will fail a lot earlier than if he/she only bends to the
pitch required. The reeds I suggested (5 draw, 7 blow, 4 draw) are ones
known to fail often. I'd have to test this myself, but I think that
within a few minutes of really hard bending pressure on the 5 draw note
it will give. That's a time frame that would lend itself to a stage
show!

Think of the entertainment value! You could have a big screen with all
the different models under test and their scores lit up. Whenever a reed
fails there could be a loud cracking or explosion sound through the
sound system, to cheers or boos from the audience. A bar at the back of
the room would keep everyone lubricated while the intrepid testers do
their work, in shifts if necessary. Even if nothing conclusive came out
of it would be a lot of fun!

Brendan
WEB: http://www.brendan-power.com