Tuesday, May 24, 2011

Kashu-do (歌手道): Understanding fold function: Part 1 Fold Structure

Our goal in phonation is an efficient, flexible and fluid vibration of the fold cover, what some refer to as singing on the thin edge of the folds.  Traditional vocal language is full of jargon based on singers sensations and indeed the physical act of singing has to be a sensory experience.  There is not a lot of time for the brain to control.  The brain's job is to conceive of the desired sound.  The body must more or less automatically produce the sound, which yields specific sensory feedback.  Those sensory experiences become the tools we use to recall the correct (or in some cases incorrect) function.  The sensory experiences may be transmitted from teacher to student via a technical approach that brings the student to those experiences.  Imagery and sensory-based jargon can work, however jargon must be based on actual function, otherwise it can be confusing.  Sensations that are very similar (and to the student sometimes undistinguishable) can be the result of good and bad function.  For that reason, the teacher's ability to distinguish between correct and incorrect function is crucial, particularly with respect to equivocal sensory feedback.  Consequently, I have spent the last month researching this particular post.  Some fundamental claims that I make here often, with regard to fold depth, lip-trills and occlusives need to be clarified.  It is imperative to understand why a tone production that is too thin relative to fold depth would yield a sensation of heaviness, and also why the reverse would also be true--that a too deep production might yield a sensation of being light and disconnected.

Fold function, as most processes related to the singing voice, is paradoxical at best, that is until the complex patterns are understood.  First the basic structure of the folds:

On the left of the picture is a medial sectioning of the larynx showing the left side.  The vocal fold is circled and an enlarged, detailed picture of the same is produced on the right side.  The picture shows the five (5) distinct layers of the the vocal folds.  Depending on the purposes of scientific research, the folds may also be partitioned into three (3) layers, from flexible to less flexible: 1) the mucosa, made up of the epithelium and superficial layer of the lamina propria 2) the vocal ligament, made up of the medial and deep layers of the lamina propria 3) The thyro-vocalis muscle or muscularis.  For purposes of high level function such as classical singing, the layers are usually partitioned into two (3): 1) the mucosa also called the fold cover and the other three layers called the fold body.

As mentioned earlier, the goal of the lyric singer is to limit the vibration of the vocal folds to the fold cover (mucosa).  There are many issues to discuss here:

1) Does the singer desire for the entire usable range to be driven by a mucosal (cover) vibration or does the deep part of the folds (body) participate in some parts of the range (e.g. the lower range)

2) Does what scientists observe and publish as norms agree with the vocal function of the very best lyric singers?

3) How does the singer produce a desirable, sustainable phonation pattern based on mucosal isolation?

See the next post for answers

I have decided that these heavily scientific blogposts need to be experienced in digestible chunks.  Consider these questions and see the next post in a day or two.

© 05/24/2011

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