Klarinet Archive - Posting 000259.txt from 1993/12

From: Cary Karp <nrm-karp@-----.SE>
Subj: Re: Did everybody die? (still waiting for acoustics lesson)
Date: Fri, 24 Dec 1993 12:39:01 -0500

On Thu, 23 Dec 1993, Jay Heiser wrote:

> I'm still waiting for my lesson in acoustics. I forgot who, but
> somebody promised to describe how a clarinet functioned [. . .]
>
> Where does the sound come out?

The sound can come out of any opening which allows pressure variation
inside the instrument to cause pressure variation outside the instrument.
The primary candidate openings are obviously the bell and open toneholes
but not all available openings will radiate sound for every note on the
instrument. (Experiment -- for every note on the clarinet, try covering
the bell and every individual open tone hole. Sometimes a single hole
will radically effect the sound, sometimes it won't at all.)

There are also strong frequency-dependent directional properties to the
way a pressure disturbance is radiated through a given hole. The wind
player's concept of projection relates to the way energy may be
"focussed" in this manner.

> How do changes in material of reed/mouthpiece/body affect sound?

Answering this one will take more than a few lines here. How's about
feeding me specific limited questions and we'll do it in installments?

> Do different pads affect the sound (I've had my most dribble-prone
> pads replaced with cork)

Pads on open keys can absorb energy which otherwise might be radiated
through the tonehole. Pads on closed keys may look like local "mushy"
spots on the wall of the instrument and also absorb energy. The energy
losses are frequency dependent where high-frequency losses are more
likely than low-frequency losses. As a general rule, therefore, more
reflective pads will favor a more brilliant sound.