[Harp-L] THE COMB DEBATE REVISITED: SPAH Test

["Brendan Power" <bren@xxxxxxxxxxxxxxxxx>]

As most of you will know, Vern Smith has conducted a couple of public tests
over whether listeners in an audience could detect differences in sound
between harmonicas with different comb materials. The result was conclusive:
they can't. Vern has offered a wager of $1000 to anyone who can prove that
result wrong, and no-one has taken up the offer. That speaks for itself!

I fully accept the results of Vern's audience tests, but now want to
investigate a different issue: what differences (if any), can players/very
close listeners detect? This issue still arouses passionate feelings, as is
shown by the way many players are very choosy about their favourite comb
materials. Should they bother? Hopefully this test will shine some light on
this fascinating and still murky area.  

There are different ways to test this issue. I'm adopting a passive
approach, simply collecting data, not seeking to prove anything one way or
the other. I'm very happy to say that Vern Smith has kindly agreed to lend
his valuable experience and expertise to my test, and in the future may
follow up with a differently-focussed test of his own. Here is a description
of the 2010 SPAH Test:

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THE COMB DEBATE REVISITED: Player, Close Listener & Spectrograph Test
Co-Conducted by Brendan Power & Vern Smith. Custom combs supplied by Chris
Reynolds

The aim of this test is to see what can be discovered about the sounds of a
harmonica with different comb materials, when listened to up-close under
controlled conditions by three parties: 1. Players 2. Close Human Listeners
3. Microphone and Spectrograph. One vexed issue we hope to shed light on is
"Can the player perceive differences in comb materials?" In doing the
testing, we will record spectrograph images of many common comb materials,
and there could be some interesting ancillary data (eg. possible tonal
differences between embouchures: Tongue Blocking vs. Lip Pursing vs.
U-Blocking).

We will use only one set of diatonic reedplates and coverplates on all
combs, from a Hohner Marine Band Deluxe. Vern has made a special bracket
which will enable fast comb changes and mask the varying weights of the
different combs. The comb smell/feels will be masked so that the different
materials cannot be sensed by lips/tongue. 

We will be testing eight materials which are commonly used in diatonic
harmonica combs: Pear Wood, ABS Plastic, Diamondwood, Corian, Acrylic,
Brass, Bamboo, Aluminium Alloy. Aside from the stock Hohner combs, the
identically sized/shaped custom combs will be made to exacting
specifications by Chris Reynolds. They will be available for sale after the
test.

There will be six test players. They will be blindfolded and wear ear
mufflers between each test (so they cannot listen to the other testers
before/after their test). They will be respected names who have different
styles and embouchures (tongue block/lip purse/U block). For the
spectrograph readings, two single test tones of 3 seconds each will be taken
for each comb: a blow and a draw on hole 4. For the test playing, each
player will choose a favourite selection of phrases which they duplicate to
the best of their ability on every comb. Each playing test will last 20
seconds. Players will note their impressions immediately after each test, in
isolation. The players will not confer or communicate with each other in any
way during the testing procedure.

The three Close Human Listeners (within 30 cm away from the played harp)
will also be blindfolded for each test, and not permitted to
confer/communicate with each other. They will also note their impressions
immediately after each test, in isolation. 

The data from the Players and Close Human Listeners will be collected via
simple unbiased multi-choice questionnaires. It can later be compared to the
Microphone/Spectrograph data for each comb. The data will be made freely
available to all after the test. 

An audience is invited to attend the test but must remain silent when each
test is conducted, and must not influence the testing in any way.

-----------------------------------

No doubt there will be many suggestions/questions about the procedures for
this test! Rest assured that Vern, Chris and I have already engaged in LONG
email discussions over several months examining all the
quirks/ramifications/implications of different elements of the testing
procedure, and have come up with what we collectively believe to be the best
possible process for a two hour test at SPAH. We are confident that our
procedure and protocols will be sufficiently rigorous, comprehensive and
balanced to produce valuable data that will add considerably to the
long-standing debate over whether comb materials affect harmonica tone. The
aim of this particular test is not to prove anyone right or wrong, but to
increase the body of knowledge about this fascinating, hotly-contested
issue. At present, it is purely a matter of (widely differing) subjective
opinion. Hopefully the results of this test will start to give the debate a
more factual basis, and future tests can build upon it to reach a widely
accepted consensus.

Brendan Power
WEBSITE: http://www.brendan-power.com
YOUTUBE: http://www.youtube.com/BrendanPowerMusic