Author: kdk ★2017
Date: 2020-11-08 20:49
This might have been a tangent off the discussion about tone in the thread about Brio reeds. But I didn't want to risk hijacking that thread. Depending on the actual state of knowledge, this may be a rich area for learning, or a complete crash and burn.
A sounding clarinet's air column vibrates in multiple modes at once - primarily over its full length (the fundamental), in thirds (3rd harmonic - the 12ths), in fifths, sevenths, etc.. The player can manipulate the strength of the harmonics through technique and equipment can tend to favor specific harmonic ranges, and in either case, the tone quality is affected.
What is the correspondence of the reed's vibrating mode to those of the air column? Assuming (as I do intuitively and from what little literature I've run across) that the reed in some way synchronizes with the air, does it react to the air column's vibrations that are determined by the instrument's length and venting, or is it a provocateur that causes the air column to split into harmonics. Obviously, when we open a register vent, the instrument is controlling the pitch. When we play "bugle calls," whether on a clarinet or on a real bugle, the reed's (lips') vibrating mode is controlling things. What about the harmonic content in normal tone production at any given pitch level? From what I *have* read, the frequencies aren't identical. But is the harmonic *distribution* the same between reed and air column?
Assuming the reed's harmonic mode is as complex as the air column's, where do the harmonic divisions occur in the reed? Does the spine vibrate as a single unit (producing the fundamental) while regions of varying stiffness as the reed thins toward the edges and tip vibrate at increasingly higher harmonic frequencies? Or does the division occur mostly along the vamp's length.
I would imagine the physical distribution of harmonic multiples over the surface or even the volume of the reed would dictate how the reed needs to be shaped to encourage or discourage the generation of specific harmonic ranges. As players most of us go by empirical experience - ours or others' - and there are diagrams in every book chapter and periodical article about reed adjustment all of which look like the diagrams that identify the different cuts of meat from a steer or hog. Scrape here and the tone becomes "darker" or "brighter" or more resistant or more responsive, etc.. Most if not all of the instructions and teaching about reed making or adjustment are grounded in "I believe", or "I feel", or "In my experience" - all based on "if you take cane out here, the result will be...".
But in the Brio thread much was said about the actual harmonic content players strive to produce. Is there meaningful, physics/(acoustics)-based mapping of a reed's vibrations that could guide players to more reliable, less guess-y adjustments?
It may be that this is a more or less moot issue, that those diagrams that we already have are enough to accomplish the purpose. Are reed designers (Bob? Brad? any input?) also guided by those meat diagrams plus trial and error, or do you work with the kind of information I'm describing?
I apologize for my long-windedness. I'm struggling a little to formulate the question itself so some of the verbiage is my own attempt to clarify the problem in my own mind.
Karl
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The Clarinet BBoard
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