Fwd: [Harp-L] Single reed bend (simple question)

["Winslow Yerxa" <winslowyerxa@xxxxxxxxx>]

--- In harp-l-archives@xxxxxxxxxxxxxxx, Zombor Kovacs <zrkovacs@xxxx> 
wrote:
Folks

I have posted my question earlier, but did not get an
answer so I give it a try again. Lets take hole number
1 for example on a 10 hole diatonic harmonica. There
is a valve on the lower reed, so this cannot
participate in a blow bend. Why does the sound become
deeper in picth (lower frequency) if I (blow) bend it
down? 

====Winslow

Just blowing harder will only depress the pitch slightly. To 
significantly lower the pitch you create a resonant chamber in your 
mouth. If the resonant frequency of your mouth cavity is within the 
range of pitches that may be produced by that reed in closing mode, 
it will lower to that pitch.

To create a tuned resonant cavity in your mouth requires that you 
separate this into a system that is distinct from the rest of your 
respiratory tract - windpipe and lungs. This is accomplished by 
creating a change in the airflow at a key point that will form the 
back of the chamber by narrowing the passage with tongue or throat 
muscles. As the iar must travel faster and at a different pressure 
through this point, this point separates the front mouth chamber from 
the rest of the breathing chain and hence creats a new system. You 
can tune this system by changing its size, either by moving the 
constriction point, by moving the tongue inside the mouth chmaber, or 
by using the jay to enlarge or reduce the size of the chamber.

===Zombor

OR

Lets take hole nr 1 again with the upper reed blocked
(overblow situation). I blow the draw reed. Why does
the sound become higher in pitch if I (blow) bend it
up?

=====Winslow

The same thing is going on with an added dimension. A reed may open 
or close. Standard playing uses closing reed action, where the reed 
is propelled by the breath into the reedplate slot and then springs 
back.

When a reed is played in opening mode, it is propelled by the breath 
AWAY from the slot before springing back.

A reed played in opening mode will sound, at its lowest pitch and 
with its strongest vibration, a little less than a semitone higher 
than its closing pitch.

While a reed may be played in closing mode simply by supplying air, 
opening reed action requires a bend for activation. So to get that 
draw reed to play a semitone higher by blowing, you tune your mouth 
and activate a blow bend set to a semitone above the closing pitch of 
the reed. And as a clsoing reed may be bent down in pitch, and 
opening reed may be bent up.

Plating a reedplate held up to the mouth and observing in a mirror 
(use one of the reeds that is facing the mirror) you can observe 
several things.

- Played in closing mode, the reed will vibrate most vigorously at 
its default (highest) pitch. As the pitch is lowered, the magnitude 
oif the reed vibration lessens and the reed is drawn closer and 
closer to the reedplate until it stops entirely - propbably because 
it can no longer emerge fully from the slot to "chop" the air.

- Played in opening mode, the reed will vibrate most vigorously at 
its default opening pitch about a semintone above the closing pitch. 
As the pitch is raised, the magnitude oif the reed vibration lessens 
and the reed is farther and farther away from the reedplate until it 
stops entirely - propbably because it can no longer passs through the 
slot to "chop" the air.

Does this answer your questions?

Winslow