Klarinet Archive - Posting 000102.txt from 1996/10

From: Jonathan Cohler <cohler@-----.NET>
Subj: Re: odd comment (acoustics)
Date: Fri, 4 Oct 1996 22:26:48 -0400

Steve,

That's not a simple question with a simple answer.

We all know empirically from playing that different reeds do indeed sound
differently. At the simplest level, bad reeds sound really bad, and good
ones sound good.

To make interesting comparisons, I believe we have to restrict ourselves to
talking about "good" reeds. It is my experience that on all "good" reeds,
a player sounds pretty much the same on a given mouthpiece and instrument.

The factors that make a good reed are many (and I'm sure the reed makers on
this list could discuss this in great detail), but the basics are good
cane, with a good even grain, and a proper spacing of the grain lines (I
forget the name of these), a well balanced shaping, and consistently
symmetrical thicknesses around the reed.

Once you have all that, the only significant difference to focus on is the
hardness. As hardness goes up, greater pressure on the reed is required to
maintain the optimal operating point for vibration. This takes greater
energy from the player. With lower pressures on a hard reed, there will be
greater amounts of air rushing noises from air that is not being used
efficiently to generate vibrations. It's this air rushing "white noise"
that is the fuzzy sounds that are associated with hard reeds. This
includes energy at a wide range of frequencies including non-harmonic
frequencies.

As for different hardnesses exciting different harmonics at different
levels, I don't believe this is the case. Remember that the reed and the
air column are a coupled vibrating system. The reed excites the air column
and the air column controls the vibration of the reed. If you have a nice
flat piece of balanced wood being sucked in and out by the air column
against the mouthpiece opening, it should always vibrate in the same way
(given an even mouth pressure, i.e. good embouchure). That's why all
"good" reeds sound the same on a given setup (played by a given player).

Obviously, by using different amounts of mouth pressure, different balance
of pressure, and different air pressure/tongue position, one can produce
different tone colors. Holding all these constant, however, the only other
way to change the tone color is to play louder. When the clarinet gets
louder, a larger amount of the higher harmonics enters the sound. This is
because the reed begins to hit the mouthpiece for more and more of the
cycle. Everyone who remembers their waves class from Physics I remembers
that waves which have sharp corners contain lots of high harmonics. The
hitting of the mouthpiece "chops off" the top of the wave giving it a sharp
corner, hence the high harmonics.

So the short answer is no, I don't believe that different hardness reeds
stress different harmonics.

However, I do agree that if a reed is too soft for a given setup, it won't
play the high notes well. This is not just a function of softness,
however, it is really a function of the hole balance and shape of the reed.

The trick is to find the softest reed possible that will still play
comfortably on a double high C.

-----------------
Jonathan Cohler
cohler@-----.net

At 4:10 PM 10/4/96, Steve Prescott wrote:
>My question still stands...addressed to Jonathan Cohler originally but I'll
>take anyone's response:
>
>Do different reed strengths emphasize certain harmonics? Could this be what
>we perceive as dark and bright sound? As Jonathan pointed out, harmonics do
>play a part in bright vs. dark sound. Maybe a softer reed stresses lower
>harmonics, thus making the upper register sound flat. Am I all wet here or
>what?
>
>Steve.
>
>Steve Prescott
>Instrument Rep.Tech./ Clarinetist
>Indiana State University
>mipresc@-----.edu