Re: [Harp-L] end to end reeds

[Vern <jevern@xxxxxxx>]

Unless the comb were unusually thick, the longer, low-pitched reeds would strike each other.  Otherwise, you can get a pretty good idea of their behavior by blowing the Cs in holes 4 and 5 of a chromatic that are linked through the player’s embouchure. If they were not identically tuned, they would beat. 

 I doubt that their position side-by-side or facing makes much difference.  Each reed can affect and respond to the overall pressure in the chamber but no directional waves would travel from one reed to the other.  For this reason, although a reed can feel the pressure variations created by the other reed, it has no way of knowing where the other is. The size of the chamber is so small with respect to the wavelength of the sound that no directional waves/effects can exist. See “diffraction” on Wikipedia. The pressure in all parts of the chamber is almost equal at any instant.  At 1125 ft/sec, a local pressure disturbance reaches all parts of a .5” chamber in less than 37 microseconds.  Thus there is interaction but it doesn’t depend on the relative positions of the two reeds.

Every hi-fi buff knows that only one woofer is required and that it doesn’t matter much where it is placed.  That is because the wavelengths of the bass notes are longer that the dimensions of the room and thus are not directional. Shrink that down to the size of the harmonica reed chamber and it works exactly the same way.

I hope that I haven’t given so much background that the foreground has gone underground.

Vern


> On Nov 26, 2014, at 9:33 AM, Larry Sandy <slyou65@xxxxxxxxx> wrote:
> 
> 
> ……….. if two identical reeds shared the same slot, facing each other on their moving ends. Unlike those reeds that are located side by side in a common slot.  This configuration should permit four reeds within the same enlongated slot, two draw and two blow.
> 
> LL
> 
> -