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

["Vern Smith" <jevern@xxxxxxx>]

----- 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


> Zombor;
>              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
> this.
>             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.
> RD

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.

Vern