Wednesday, July 23, 2008

Tension and Release: A paradox of strength

The most common concepts I hear among singers singing professionally are those of “connecting to the body” and “releasing the breath”. What is however difficult is getting a simple answer from them as to what these terms mean. To make matters more difficult, I also hear the phrases “connecting to the breath” and “releasing the body”. So where do we begin with this constant “chicken and egg” story? As always from the science!

Connecting to the body or to the breath, like most terminology based on proprioception, is an attempt to explain a resultant sensation when the causal functions are not understood. The confusion comes from not understanding the inherent paradoxical nature of singing. The majority of singers and teachers of singing do not like the term, “tension”. It is easier to refer to the tension that is felt when the voice is properly functioning in euphemistic terminology like “connecting to the body” and “engaging the breath”. Some prefer to avoid all sensations of tension and speak only in terms of “release” and “relaxation”. Whatever one-sided terminology is used will result ultimately in imbalance. Balanced singing is based on contrary forces acting upon each other to create a state of stability, while very energetic work is being performed. No viable aspect of “acoustic singing” (i.e. unamplified operatic singing) is performed without tension. That tension however is balanced tension.

What is it then that gives the sensation of connection to the body or the breath? It is simply the sub-glottal pressure that is created when the vocal folds close fully against the oncoming breath. For that reason, I take a line from the many axioms of a great voice teacher, Lloyd Hanson, who says: “There is no discussion of breath support without first assuring efficient phonation.” (I paraphrase). If that is all that is needed for that feeling of connection, why don’t we do everything possible to simply get the vocal folds to come together fully? Many people do just that! The result is often what we refer to as excessive medial pressure or “pressing”. There are many unbalanced ways to get the vocal folds together when “release” is not part of the equation, which begs the question: “What is release, and how is it compatible with tension?”

The truth is that the right amount of tension is not possible without the correct means of release. I have discussed here extensively regarding the balance of musculature that produces efficient phonation. We must assume first of all that those muscles (primarily, crico-thyroid, thyro-arytenoid [lateral and vocalis], crio-arytenoid and inter-arytenoid) are functioning in balanced antagonism with one another, thereby producing a phonation model that is efficient. In such a model, the vocal folds come completely in contact during every adduction (closure) cycle. Such a balanced muscular state cannot be possible unless the tongue is not interfering with the phonation process. Therefore, it is presupposed that the tongue is functioning as it should. Given that the tongue is the primary element of resonance, it follows that resonance function is also correct enough to support the phonation process as opposed to hindering it.

In the correctly functioning voice, resonance is indeed the agent of release. When the vocal tract is properly tuned with the sung pitch (fundamental and overtones), the air, above the vocal folds, assumes a remarkable acoustic state called, “supra-glottal inertial air.” In this acoustic state, the air above the glottis behaves in concert with the movement of the vocal folds, acting like a vacuum (negative pressure) that one moment accelerates the close phase and then like a leaf blower (positive pressure) increasing the opening phase the next. The vibration of the vocal folds therefore covers a larger distance (amplitude), however the accelerated close phase is fairly quick. This can also be called a comparatively much more efficient vibratory model whereby the close phase is quick and complete and the open phase allows for greater airflow.This “glottal impedance” occurs only when the vocal tract is in consonance with the sung pitch (i.e. one of the formant spaces [above or below the tongue] is in tune with the fundamental or one of the overtones of the sung pitch).

In a sense, it is not helpful to talk about phonation and resonance (tension and release) in terms of the chicken or the egg. The ideal resonance adjustment that produces glottal impedance cannot occur without a full glottal closure that is independent of extraneous tension. Likewise, balanced phonation cannot exist in a situation whereby extraneous muscular tension deforms the ideal dimensions of the vocal tract.

As per the title of this issue, the ideal balance of phonation and resonance depends on muscular strength. Each set of muscles must be developed strongly enough to function in concert with its antagonistic counterparts. Even a weak set of crico-thyroid muscles can stretch the vocal folds of a basso profundo to create a high C. Of course that high C would be in falsetto. The issue therefore is not whether the CT can stretch the vocal folds adequately, but whether they can while enduring the kind of antagonistic action from the vocalis muscles, to produce lengthy vocal folds that are bulky enough to resist the power of the sub-glottal air pressure. If not, then the vocalis will win the tug-o-war and the pitch will lower. Likewise, it is important that during this action that the inter-arytenoid muscles can complete the closing of the glottis. That too is an issue of strength. In the case of singers who do not have easy high notes, the issue is one of strength building over time. High notes come gradually when the singer slowly and deliberately practices higher and higher notes, developing strength in them such that they can withstand the sub-glottal pressure necessary for performance level volume.

Ideal resonance and phonation is a natural state that was trained in us as we developed the vocal capacity to make sound as babies. These sounds communicate primal needs. Watching a baby cry or laugh with joy shows the complete function that we as singers aspire to. The greater paradox in all of this is that most singers attempt to learn something they always knew how to do.

© 07/23/2008; corrected 07/25/2008

8 comments:

petersjj said...

I love your blogs. I really do.
I hold them in such regard and I ALWAYS look forward to reading them.

If I'm right on track with this, the resonators then have to match what the larnyx is "saying".

Correct?

Toreadorssong's Vocal Technique Blog said...

Exactly. Although we feel vibrations in our faces (mask) head, chest, etc through bone conduction, the only true resonance occurs in the vocal tract which is divided in two by the tongue: first formant space below the tongue and second formant space above the tongue, which have pitch (frequency) relative to the vowel that is being sung. One of the these subspaces of the vocal tract (from top of vocal folds to edge of lips) will be in tune with the sung fundamental or one of its overtones. Our job it to make sure, by vowel modification that the frequency of the formant space is in tune with the fundamental or one of the overtones of the sung pitch.

Thank you for your supportive comment. I try to write when I have a well-organized thought. Feel free to email me if there is a subject you would like to see addressed here. Warm regards from JRL

George said...

Interesting post. I understand what you mean about that feeling of cord closure and subglottal pressure. And you're right, if you focus too much on achieving that it's easy to press the voice. When I have found this sensation in the past it has taken less than a week before I'm seriously pressing my voice out of balance, so I go back to "release." It's such a tough tightrope to walk.

A question about resonanace. What tools do you recommend to help tweak resonance adjustments? Do you recommend using those Berton Coffin vowel charts? I know you've mentioned voce vista for real time feedback, but I don't think they make the program for Mac.

Peace,
George

Martin Berggren said...

Thanks for a wonderful series of articles on vocal technique. It is a pleasure to read them, and they are always very insightful and helpful. However, I feel I must gently object to the following:

[you wrote..]
...a remarkable acoustic state called, “supra-glottal inertial air.” In this acoustic state, the air behaves in contrary action to the movement of the vocal folds, acting like a vacuum that one moment impedes the closure of the folds during the close phase and then resists the opening phase the next.
...
Glottal impedance in effect prevents the vocal folds from closing too tightly during the close phase and to open too far during the open phase. The vibration of the vocal folds therefore covers a much smaller distance. This can also be called a comparatively much more efficient vibratory model.

My understanding of the effect of supra-glottal inertia on phonation is different (well opposite really...) from what you express above. When the vocal folds are in the opening phase, the air pressure coming from below glottis accelerates the supra-glottal air column. In the case of inertial reactance (in the case of harmonics with frequencies less then the first formant peak, for instance), it takes some time for the air column to accelerate due to inertia (this is the meaning inertia: "sluggish" reaction to imposed forces). There will thus be a pressure build up just above the glottis (it is this pressure build up that accelerates the supraglottal air column). But that pressure build up will also act back on the vocal folds, forcing them to open more compared with the case when there is no inertial reactance. In the closing phase, the effect is reversed: the air column continues to move due to inertia, creating a supra-glottal suction that tend to force the glottis to close quicker, compared to the case of no supra-glottal inertia. Thus, supra-glottal inertia tend to increase the oscillation amplitude.

The mechanism I describe above is a "linear" effect that gives feedback from the vocal tract to the vocal chords to help maintain a self sustained oscillation even in the case when the folds do not collide. Thus, an oscillation have a higher chance of being self sustained when the supra-glottal load is inertive.

In addition to the above, Ingo Titze (among others) has also argued that there are nonlinear effects caused by inertial loading that cause a skewed flow pulse and thus a richer harmonic content, again without the need for vocal cord collision.

Cheers,

Martin Berggren

Toreadorssong's Vocal Technique Blog said...

Thank you Martin,

I have trusted the information I was given by a trusted source on the subject, but it seems that information was superficial. I thank you for the correction, and will do some more in depth reading on the subject. Please feel free to comment whenever you notice errors of this sort. I will amend the column here after I have read on the subject adequately.

Much much appreciated.

JRL

Toreadorssong's Vocal Technique Blog said...

Dear Martin,

Titze's Singer friendly articles on NVCS cleared the confusion. I reversed positive and negative pressures in my head. Here is what Titze says in complete accordance with your correction of my statement:

...the motion of the supraglottal air column provides a positive pressure above the folds for glottal opening and a negative pressure for glottal closing. This is precisely what is needed to drive the upper part of the vocal fold.

The discussion I had with my source influenced me to think that the positive pressure during the open phase would counter the opening and similarly, the negative pressure would hinder the close phase. Since negative pressure is vacuum-like, I see where I made my error. The negative pressure would essentially create a vacuum state between the open folds, sucking them in, correct?

Questions for you then? Is a larger amplitude of the fold vibration more efficient? Am I understanding that the increase amplitude which I assume would increase flow is desired in the greater scheme of balance? In other words, without the increased flow caused by S-GIA would conditions cause too much sub-glottal pressure?

Toreadorssong's Vocal Technique Blog said...

Dear George,

Coffin did some good work, but discussing the issue with some scientist friends, it seems Coffin did not consider the second formant in his vowel chart. So while resonance would be achieved with the chart, it would be based on formant 1 tuning, and this would not help the classical singer as much in the upper range. Now giving if we take Giuseppe di Stefano as an example, there are singers with such flexible vocal folds that they are able to manage the entire range with first formant dominance.

The concept that I use relative to resonance tracking is maintaining what I call the default size of the vocal tract. If the laryngeal depth is more or less constant as is jaw release, and palatal height, the main factors in resonance become the tongue and lisps (i.e. vowels). If we chose one given vowel, and maintain the dimensions of the vocal tract flexibly constant, the change from formant 1 to formant 2 dominance in the passaggio would be automatic with only minor changes in tongue and lips. Resonance adjustments should not be addressed in my opinion until excellent phonation has been achieved as well as the ideal default dimensions of the vocal tract (i.e. released jaw, natural laryngeal depth and released soft palate including velar closure to avoid nasality).

Martin Berggren said...

Dear Jean-Roland,

[you said...]
The discussion I had with my source influenced me to think that the positive pressure during the open phase would counter the opening and similarly, the negative pressure would hinder the close phase. Since negative pressure is vacuum-like, I see where I made my error. The negative pressure would essentially create a vacuum state between the open folds, sucking them in, correct?


Yes, the lowered pressure help to suck the folds together. The whole process (pressure increase when the folds are opening and pressure decrease when the folds are closing) is an example of "positive feed-back" that helps maintain a self-sustained oscillation.

[you said...]
Questions for you then? Is a larger amplitude of the fold vibration more efficient? Am I understanding that the increase amplitude which I assume would increase flow is desired in the greater scheme of balance? In other words, without the increased flow caused by S-GIA would conditions cause too much sub-glottal pressure?


Well, I think the issue is ease of phonation, or, in scientific terms, the "phonation threshold pressure", the minimum lung pressure needed to sustain oscillation of the vocal folds. An increased inertial load makes it possible to initiate sound at a lower lung pressure and increases the sound intensity at a given lung pressure above the threshold level. We are able to extract more sound energy from the steady flow of air.

Note that to say that an increased (decreased) supra-glottal pressure aids in opening (closing) the vocal folds, it implies an implicit assumption on the vocal fold motion: the reasoning makes sense when the vocal fold motion is of the "two mass" type, that is, each side of the folds acts like a lumped mass attached to a spring. This motion may (if I understand things correctly) be a crude model of what happens in a head voice or falsetto register. However, the vocal folds can also support a motion in which a wave travels vertically upwards in the glottis. This "mode of vibration" occurs in the modal (chest) register and appears to be quite insensitive to vocal tract interaction.