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Re: Mouthpiece and legere reeds

Author: shmuelyosef
Date: 2019-01-24 00:12

In full disclosure, my undergraduate studies were in acoustics in an electrical engineering department. I have often referred to the New South Wales Dept. of Physics website on The Clarinet, and there is some insight there regarding pitch shifting.

...de rigeur is a review of the basics of mouthpiece/reed/embouchre:

http://newt.phys.unsw.edu.au/jw/clarinetacoustics.html#reed

The relevant 'meat', however, is the section a few paragraphs down that is labelled "Playing loudly and softly", however, for this discussion, it could as well be labelled "Playing flatter or sharper"

http://newt.phys.unsw.edu.au/jw/clarinetacoustics.html#pff

We all know that blowing hard (high pressure) and playing loud tends to make the clarinet flat. A resistive reed also makes the pressure higher. My hypothesis is that the Legere reeds are slightly more 'lossy' than cane reeds in general, which is why the Classic reeds were always stuffy to play on. In a reed being played optimally, the reed hits the mouthpiece and stays closed for a brief time (call this the "dwell") then pops open. While our airflow drives the reed closed, it is the reeds 'return power' that reopens the reed. A stiff reed with no loss returns much faster that a floppy reed with some loss. This means that inherently this is a 'drag' on the oscillation frequency.

If you look further down in the document:
http://newt.phys.unsw.edu.au/jw/clarinetacoustics.html#acousticimpedance

The discussion of acoustic impedance is very important and also has some intuitive interpretation. I think most of us that are engaged in this discussion understand that the body of the clarinet acts as a resonator that filters the input from the mouthpiece/reed and, in fact, acts as a control point to only allow the reed to oscillate within a small range of frequencies. We all also know that there are strong notes (middle chalumeau, e.g.) and weak notes (throat tones and altissimo) on the clarinet. The strong notes are fingerings that have a narrow resonance (small range of frequencies with a strong emphasis) and the weak notes (larger range of frequencies with a weak emphasis). It should be no surprise therefore, that the throat tones exacerbate what some have experienced with the Legere EU sig reeds.

A simple summary, therefore, is that the spring constant and lossiness of the reed can make a reed more or less susceptible to the influence of the clarinet resonance structure (as an aside, we all know of mouthpieces that play sharp or flat, and a similar argument applies to the facing curves...some more lossy or biased than others). Legere is making reeds from a material that has quite different mechanical parameters than cane (although it is much more consistent than cane). In pursuing a better responding reed, they have made them progressively thinner, which changes the dynamics and leads to the discussions we are having.

Regarding facings, I would hypothesize that there could well be a variation of facing design that is more optimal for the Legere reeds; for example, varying the curvature to match the binding modulus change as the reed curves over the facing curve could be an excellent strategy. We all know, for example, how mouthpieces respond differently to Rico vs. Vandoren reeds, and yet we are surprised when polycarbonate responds differently than cane.

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Mouthpiece and legere reeds new

Yador

2017-12-21 04:12