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From: Bobbie Giordano
Date: Mon, 2 Dec 1996 05:58:48 -0500 (EST)
Subject: Bends with Resonance

Well, guess I'm feeling feisty here in Tallahassee where my hometown,
alma mater just served up the main course, flame-broiled gatortail! :)
But, you all also know this subject is one of my faves...

A discussion continues between fjm and Mike disputing the influence or
impotence of resonance in bending. Winslow has mentioned amplitude in
observing different bend types. He and Pat have brought me around to
accepting transference of pitch between reeds [well, actually, confirm-
ing it, as I test some of my ideas holding the harmonica, sans plates,
vertically while I play notes, and have always noticed the reed activity
trade-offs by the sound shifting between my left and right hearing. But
I don't think I was clear about that in my posts with them.]

Oops. That reminds me...left and right...almost forgot. Be back on that
soon...promise! And then I'll unsub!

Anyway, Vern reiterates Helmholtz. Thanks for the formula again, Vern. I
remembered to save it this time. And he mentions that the ocarina is a
Helmholtz operative instrument. I have one, shaped like a torus [donut]
and can agree with him that the volume inside is constant, but...Hmmm. He
says the "pitch is controlled by varying the total area of the opening[s]"
but I'm not so sure. On my ocarina, like any, the breath hole stays the
same size but the angle of my breath can affect a change in pitch. I can
make it change a whole third...from a C up to an E, not counting octave
jumps by force of breath. However, the hole size does definitely impact
on the pitch of the instrument, as I discovered by playing it by using the
fingerholes as the blow holes instead. Hey, seemed like a good idea to
me! And yes, blowing across the smaller fingerholes does produce lower
pitched tones for the instrument's "basic" note than when blown through
the designated "blowhole", which ties in with Helmholtz theory. But, what
fascinates me is how I can lower the pitch by using a shallower angle of
breath direction in relation to the hole, and raise the pitch by tilting
the instrument down, thereby increasing the angle of the airflow direction
relative to the plane of the hole's surface.

Now, a "true" Helmholtz bottle is a spherical container with an open hole,
across which passing air creates some audible tone. But the same principles
are extant and relevant in containers of proportions other than spherical,
and the angle of air flow can incite tones of pitches other than the primary
pitch of the container. I must admit that in most types of bottles, closed
tubes, cylinders and the like, there IS one basic tone characteristic of the
container, but in some, like my ocarina, the secondary tones seem to have
the same strength, volume and stability as the primary tone [whichever one
THAT is!] And also, some of the notes played by lifting the finger[s] sound
more easily with the instrrument tilted one way more that the other. [No
wonder I can't play the danged thing!]

What has this got to do with resonant bending? I'm trying to remember
myself... I guess it's that the air movement across the helmholtz bottle's
mouth excites the air molecules of the interior to vibrate, and they do
so audibly when the external air disturbance is vibrating in sympathy with
the interior air. There is one vibrating frequency that best matches the
interior air's preferred frequency that is reinforced by the container's
dimensions, and in my view [please note the qualification,] the material
of the container, yet, other frequencies may also be able to be tapped.

In a harmonica, [See? Real harp content.] we set the air to vibrating in
little chambers where metal reeds reside, and these reeds, because of their
size, shape, and perhaps myriad unknown properties, have the capacity to
wag in the wind, chopping up the air flowing past them and through the
narrow slot in which they barely fit, so as to make a soundwave. The tone
they make with the least air movement is the tone we use to guide us where
they are located along the harp, so that note will be the easiest one to
produce with that reed in a prescribed and ordered hole. I surmise that
note is also the fundamental resonant frequency of that reed, but it also
has the ability to vibrate at secondary frequencies if somehow caused to
vibrate in an unnatural fashion.

A couple things bothering me...Winslow seems to see a connection between
the reed's amplitude and it's changing pitch as the notes bend. I presume
he refers to the visual nature of the vibrating reed, and seems to feel this
supports his [and Pat's] idea that the two strongest pitches of a harmonica
reed are its natural note and its opening bent note. I've observed the
reed action as he did with mirrors [no smoke] and feel the reed is most
active when sounding the natural pitch, but is about the same whether it
is sounding the lower closing bend or the higher opening bend, provided
the same air pressure is maintained for all of them. I have two hypotheses
about this: one, that the visible amplitudinal variations diminish in
extremes as the notes get further away from the natural tone of the reed,
whichever direction the pitch fluctuates; and two, that bending notes
requires the reed[s] to be activated in such a way as to cause vibration
of other areas of the reed[s] besides the tip [i.e., the thicker middle,
or perhaps even more precisely the tip for some pitches.] My reasoning
is that other combinations of harmonics and overtones are necessary to
create different pitches with the same reed. To do so, proper resonance
will help "sustain and reinforce" the selected tone, but I don't see how
resonance can be the causative force in what note a reed makes. Resonance
is a phenomena that "happens" when bodies vibrate sympathetically, not
what "makes" them vibrate in such a way. As I see it, and "feel" it, it
is subtle changes in air flow, pressure, direction, volume and such that
are primarily responsible for initiating a variation from the normal note
of the reed.

I reiterate that I believe the only "strongest" pitch of the reed is the
one it sounds naturally with wind activation, and for all of the reeds,
that is a closing reed sound. All other tones require embouchure and
breath manipulations to achieve, and resonating adjustments [with the
throat, diaphragm, upper and lower respiratory tract, embouchure, hands,
etc.] to perform them with good tone. It's a grab bag!

So...hang in there [finish soon!]... obviously, I'm back again to my old
refrain of disagreeing with thrust of the theory of "resonant/nonresonant
bending" as promoted by Mike C....

> Resonant bending couples a second resonance to the single reed, thereby
> pulling the frequency by (not resonance coupling, but) overcoupling.
>
> Apparently, nonresonant bending requires an "external" resonance (that of
> the second reed) to change pitch. Resonant bending does not. Nonresonant
> bending doesn't work on valved harps.

He also claims that "nonresonant bending" is done with a smaller mouth size
than "resonant bending," and that he can do both types of bends...I'll be
good. Well, so can I, using either type of mouth size, but I wouldn't call
it resonant/nonresonant bending, because I get the reed to bend by altering
the way I direct the air at the hole more than anything. I can make it
sound fuller, rounder, "fatter" and all that good stuff by adjusting the
shape of my mouth, throat, hands, etc., but the bend relies on my maintain-
ing that air flow pattern, or forget it!

Now I did say I agree with Winslow and Pat about the trasference of energy
from one reed to the other, and it seems to be dependent on how close you
are getting to that lower reed's pitch. BUT, with careful manipulations,
and way more practice than I like to admit, I have managed to bend a third
hole on a D diatonic [Oskar] all the way down and work it so that either
the blow OR the draw reed handles the lowest bend. [Honest, W and P!!] Now,
I guess that second way is the way Winslow and Pat refer to as how it goes,
and I agree, that is usually the way it develops; and I suppose the other
way is what Mike is referring to, where the draw reed holds onto the bend.
What I had to find out, though, and can sometimes even do, if lucky, is
to play the lowest bent note in the hole and [with covers off] tap the
blow reed then the draw reed, back and forth and still maintain the note.
It's not "pretty" but it is possible, indicating that both the blow and
the draw reeds are playing the note simultaneously...but hey, why not?
Isn't that what resonance is all about?

BTW, Winslow, when I said:

I noticed this by bending notes all the way along the
harmonica and alternately damping the draw reed then the
blow reed, altering my embouchure several ways and times,
with each hole, and repeating the experiments quite a number
of times and ways with each hole. I still found, as I played
the bent note, that damping the draw reed killed the note
while damping the blow reed might affect the note, perhaps in
volume or even pitch, but the bent note could be made to
continue to sound, whether it was a drawbend or a blowbend.

And you responded:

Seems to me it's 50-50. Blow and draw each do exactly half the
work. The lower you go in a two-reed bend, though, the more the
(lower) opening reed contributes, whether blow or draw. The
higher you go, up to un-bent note, the more the closing reed
contributes.

This I tend to agree with, but I have had success in manipulating the
situation to where the closing reed continues to contribute the most
[and in fact, when the blow reed is touched, the bent note - sounded by
the closing reed - actually goes further down.] Obviously, I can't
accomplish this on ever hole and in every bending situation.

Were the notes, in all cases, bent down all the way? If not, in
a shallow bend the closing reed might still have been doing most
of the work.

Here was a misunderstanding. No, not in all cases did I bend the notes
down all the way...I was saying that I testing bending all the way [on
all the holes] along the harmonica. But I did test with full bends and
semitone bends, as in the 2nd or 3rd holes, on all the holes. And also,
yes, one of my "better" tuned harps I used was an A Filisko, since you
asked that, too.

Ok, ONE last point, I promise [I really want to respond to a post from
Pat also, but think I better make it separate...cool your heels, Pat! :)]
About my mentioning that:

I discovered that in hole 7 of my G S20, I can overdraw and
even blowbend down to the F# of the draw reed!!

Winslow asked:

> Do you mean you can overdraw the G# overdraw down to F#?

Nope...no Twilight Zone here. I was saying I can overdraw the hole, as
well as blowbend it down to the F#.

> Of course in Holes 5 and 7, where the reeds are tuned only a
> semitone apart, it's easy to trick yourself into thinking you're
> bending the higher reed down an entire semitone. If you check it
> on a chromatic tuner, you may find that it's really more like a
> quarter tone - i.e. the opening pitch of the opposite reed.

Ok, I did, and I have to confess, it sounds VERY close to the F#, but the
actual best I could do was to get it within about 15 cents of F#, and the
draw reed is in tune, BTW. Oh, well...not bad, but not perfect either!

That's it for now...I quit! Pat...you're next! >;)

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