[Harp-L] The comb materials debate

["H.T." <imanonimous@xxxxxxx>]

Seems to be two fundamental questions in this debate:

1. Does comb material affect tone?
2. If so, can the affect be heard by humans?

I'm not familiar with the previous comb tests done at SPAH, but the  
discussion has me wondering if there have been any tests using  
completely off-the-wall comb materials like styrofoam, rubber, paper,  
cardboard, or "Great Stuff" foam?  How about combs surfaced with a  
layer of felt inside the reed chamber? If a radical departure to  
materials that seem, on the face of it, to be completely inappropriate  
for harmonica combs demonstrates an audible affect on tone, then THAT  
question would be settled and the discussion could move on to just how  
much affect the various "normal" materials have rather than an  
argument about whether there's any at all. I would expect a styrofoam  
comb to sound like crap, but does it?

I believe (but don't KNOW) that the comb material does indeed affect  
the sound that emanates from the harmonica as a whole (not just the  
reed), but I'm not convinced that humans can discern the differences  
reliably if at all because it hasn't been demonstrated convincingly.   
Sound waves are reflected by various materials in different ways, and  
different materials have more or less affect on those reflections at  
different frequencies. The sound waves generated by the reed will  
collide with the comb material, and the material will either absorb or  
reflect the sound energy to varying degrees depending on the  
frequency, in accordance with it's relative density and the nature of  
the material's surface finishing (porous, smooth, hard, soft). Thus  
the same material might affect the reed on hole 10 to a different  
degree than it does on hole 1 because of the different frequencies  
involved. Is the chamber too small to have a significant affect?  
That's more than I can figure out.

Same things would apply to cover plate materials: Anyone ever try  
lining them with felt? I would expect that a felt lined cover plate or  
a styrofoam comb would sound like crap.

I also wonder about the reed plate's affect. Once mounted, isn't the  
plate effectively coupled with the comb, and might its ability to  
transmit vibrations from the reed to the comb material (thus using up  
energy from the reed) also vary with frequency. Has anyone tried  
mounting reeds directly to the comb material? A reed plate on a steel  
comb would seem superfluous unless the plate itself has some affect on  
tone (or just makes the harp easier to manufacture). But would a reed  
mounted directly to wood create a different tone than one on a brass  
reed plate?

Somebody on this list may have already mentioned that in blind  
listening tests humans are likely to interpret a small change in  
volume as an improvement in sound quality. We are very easily fooled.

I doubt the argument will ever die no matter what testing  
demonstrates. There are folks who pay thousands of dollars for 15ft  
speaker cables because the maker tells them they can carry frequencies  
that their dogs can't even hear. I'm certain that almost everyone in  
any audience doesn't know or care what a harmonica's made of and cant'  
tell the difference, just like they can't tell by listening if you use  
JBL or EAW speakers in your PA, or whether they're line arrays or  
boxes. They also don't know or care what kind of microphone you're  
using, or whether you have a vintage amp or a modeler; that stuff is  
all about how the player feels, which of course affects performance.  
As long as they hear reasonably good sound quality and the melody, all  
that matters to an audience is the music and the quality of the  
performance. I say, if it feels good to play it, it's workin' some  
kind of magic so go with it. Not every mystery needs an answer.

Harry