Re: Subject: Re: [Harp-L] comb material

----- Original Message ----- From: "Rick Dempster" <rick.dempster@xxxxxxxxxxx>
To: <harp-l@xxxxxxxxxx>; "Zombor Kovacs" <zrkovacs@xxxxxxxxx>
Sent: Wednesday, April 18, 2007 5:32 PM
Subject: Re: Subject: Re: [Harp-L] comb material

             Re. "The tuning fork issue". OK. But what about  (seeing
as you appear to be referring to my post) the "music box issue"? The
tines of a music box are smaller than the reeds of a harmonica. But when
you place the tiny, tinkling, barely audible music box movement onto a
solid wooden surface, bingo! it becomes loud (that is why the thing is
always screwed into a wooden box)
            A harmonica, or a harmonica plate does not behave like
            I do not quite know how the music box tines differ from
the harmonica reeds, but I suspect it is because they are not
independently mounted, but are part of a 'parent' material, the various
reeds all being part of the same piece of metal; something like the
tuned zones on a Carribean steel pan.
           If you are reading this Vern, I wonder if you might be able
to add something to this speculation.

The vibrational energy of a harmonica reed can be made louder by attaching it to a soundboard. I made a little device for determining the pitch of a reed without mounting it in a reedplate. I glued an1/8" thick plywood bottom into a large tin can. On the plywood, I mounted a little clamp that would hold a harmonica reed. When I plucked the reed, an electronic guitar tuner placed in the can could "hear" the reed and report its pitch. The plucked reed sounds much louder on the device than it does in a harp.

The reason a soundboard is ineffective in a harmonica is that the main sound from the blown reed is so loud that it masks the much quieter emanations from the soundboard. The soundboard is putting out sound OK, but you can't hear it. Masking is a well-established phenomenon of human hearing.

I suspect that the reeds of most music boxes are larger and stiffer than are harmonica reeds and are thus capable of storing more vibrational energy. I doubt that they go as low as C4. Even so, you would have a tough time hearing your music box while playing your harmonica.

I made a harmonica with an extra reed attached to the reedplate which protruded from the back so it could be easily plucked. It wasn't loud but could be heard. When playing the same pitch on the harp, the plucked reed can not be heard. This is an experiment that any of you could easily repeat to check my results. All you need to do is blindfold a listener and tell them to indicate when they hear the reed plucked.

The stars are just as bright in the sky during the daytime as they are at night. However, you can't see them because their light is masked by the much brighter diffused light from the sun. It is a matter of signal-to-noise ratio.


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