CT-Vocalis Balance: the first step to efficiency

Those we call natural singers have over time developed a muscular balance in speech that promotes the most essential component to great vocal coordination. It is true that all the laryngeal muscles that participate in phonation work in concert, but in my teaching and especially in my own change to tenor (which is becoming really exciting) I have found that dealing with the basic two-part tug-o-war of vocalis vs. crico-thyroid influences the way the other muscles respond.

The principles I have learned are the following:

1. The voice is an automatic instrument whereby the brain sends signals throughout the body to produce the “desired” sound.

2.The desire to produce sounds in speech develops in an unconscious manner (i.e. through years of unconsciously copying the voice or voices of those around us).

3. Long term vocal habits promote a specific balance between vocalis and CT that determines the weight of the voice (i.e. the relative mass, length and tension of the vocal folds on a given fundamental frequency as well as the breath pressure strategy that comes with it).

4. Most importantly, strategies can be developed through changes in breath pressure/volume that would help to effect changes in the basic muscular balance.

Understanding that falsetto requires vocalis passivity (i.e. no activity in the vocalis muscle) and that pulse range (vocal fry) requires a minimal of CT activity, the extremes give us a manner of determining what the baseline strength is for these muscles. In other words, how high can the singer sing in a light falsetto (i.e. how far can the CT muscle stretch the vocal folds when not opposed by vocalis)? And conversely, how low can the singer sing in pulse range (i.e. how far can the vocalis shorten the folds when unopposed by CT)?

It is further understood that the vocalis is dominant in the range below and including part of the male passaggio, and in the range below and including part of the female second passaggio. Singing in the range where the vocalis is more active (i.e. the lower and middle range) will have an effect of strengthening that muscle group. Likewise, singing the high range above the passaggio where the CT is dominant will have a strengthening effect on the CT muscle group. Even falsetto singing can have a strengthening effect on CT just as pulse range singing can have a strengthening effect on vocalis. The development of lower notes signals vocalis strengthening as the development of upper range signals CT strengthening.

The goal however is a specific interaction between the two muscle groups that promotes a gradual change in muscular balance as the singer goes from low to high range, across the passaggio where there is a delicate balance between the two muscle groups. First it is important to determine when the voice is out of balance. Some signs thereof include:

1. Difficulties in the passaggio is the first sign.
2. The inability to have dynamic control in the passaggio and upper voice
3. The inability to sing high notes comfortably
4. The inability to sing low notes
5. The inability to sing loudly in the extremes of the expected range

To correct the imbalance poses some problems in approach. I have found that many teachers are not interested in the in-between stages of correcting muscular imbalances. The majority of voice lessons that I have observed have revealed the teacher’s desire to get a final product in the moment.

However, when there is a muscular imbalance, an immediate solution is not possible unless extraneous muscles participate, which in turn promote the participation of other extraneous muscles to achieve a balance froth with tension.

Assuming that no extraneous muscular tension is involved in the phonation process, there is still the possibility of variation in the phonation mode. Any given note can be sung with a certain amount of variance in the mass of the vibrating edge. Accomplishing the ideal weight (i.e. vibrating fold mass) for a given note has a direct influence on the length of the folds as well as the tautness. In the modal range (where both vocalis and CT are active), the mass, length and tautness of the vibrating edge has a strong effect on the manner that the folds come together.

On the one hand, a “thicker” phonation tends to be also a little more lax and may require additional activity from the inter-arytenoid muscles (IA) to bring them together for full-closure. The benefit is a richer sound. The drawback is that the thicker phonation requires increased vocalis activity, which then causes difficulty in releasing weight across the passaggio where the muscular balance switches from vocalis dominant to CT dominant. Additionally, the increased IA activity can cause pressed voice and raise the subglottic pressure to unsustainable levels that in turn would cause the larynx to climb higher than ideal and with long-term stress even cause a wobble.

While we in the vocal community make much ado of the antagonism between vocalis and CT, it is important to know that the CT is primarily responsible for the length of the vocal folds througout the modal range. The vocalis fine-tunes by determining the thickness of the vibrating edge. When we add sub-glottal pressure (breath pressure from below the larynx), the combined effect of pressure and vocalis activity can overwhelm the CT and shorten the vocal folds bringing the pitch down. (This is a simple model. As previously said, tension along the fold edge has an influence on pitch as well).

The key point to our strategies in pedagogy is the following: How much pressure can the CT handle without buckling (compromising the length of the folds and thereby pitch)? This is why the messa di voce is a crucial exercise, maybe the most important determinant of vocal balance and health. Let us consider the mechanism of the messa di voce!

In messa di voce, the singer begins softly (assume adduction is complete for every vibration cycle–Note that at low volume, a well-phonated tone can feel like falsetto) and then gradually gets louder. As the singer gets louder, vocalis activity increases and cause an increase in the vibrating mass. There is, as previously said, a given amount of possible variance in mass, length and tension for any given pitch. The key is that as we approach the thicker end of the spectrum for any given note that the CT is strong enough to maintain the necessary length and tension of the folds. If the CT buckles, length and tension is lost and the only way to achieve the desired pitch is increased sub-glottal pressure (also called vertical pressure). The pressure from below actually bends the folds upward to achieve increase tension in order to achieve the desired pitch.
When this occurs, it is dysfunctional, because when the folds are at a shorter length than ideal because of hyper-function in the vocalis, the CT will not be able to contract further for higher notes. If this state of vocalis hyper-function becomes chronic, CT hypo-function also becomes chronic thereby limiting access to the upper range as well as soft singing.

From the previous paragraph it follows therefore that the ability to sing softly and to sing high notes easily are linked to the ability to sing a messa di voce. This brings us to the difference between true dramatic voices and lighter voices singing dramatic operatic repertoire. More dramatic reperoire (e.g. Verdi, Wagner Strauss and Puccini), because of an increased orchestra size requires greater volume than more lyrical parts. The question is the following: How much subglottal pressure/supraglottal flow can the vocal folds handle without the CT buckling?

If we consider Pavarotti, we have an example of someone who began his career singing the high bel-canto repertoire and gradually assumed the heavier repertoire. This has been the Italian model for a long time. This is based on the observation that well-produced voices gain the ability to sing louder over time. This makes sense. A balanced note sung by an expert singer five years ago will be sung more loudly now because that specific coordination through exercise (i.e. daily singing) gains in muscular conditioning and will be able to sustain greater breath pressure without loss in basic coordination. Following this theory, Pavarotti maintained the ability to sing a high C throughout his life, even performing a gorgeous Bb at the Turin Olympics while sick with Cancer. The basic quality of Pavarotti’s voice was lyrical. His ability to produce great volume without stress showed that he had great strength and in balance.

The exact opposite can be said of Pavarotti’s idol, Giuseppe di Stefano who not only took on more dramatic roles earlier in his career but also sang beyond the volume limits of his basically lyrical instrument.

Those who have naturally bigger voices (i.e. greater vocal mass and commensurate muscular strength) would benefit from from working on lyricism as well. Franco Corelli never lost his top and sang many lyrical roles despite his ability to produce great volume. Assuming more dramatic roles was in keeping with his instrument, therefore there was no danger. With time, some faulty resonance issues made his ability to sing softly less reliable, but even through his late days, he was known to demonstrate quite beautifully for his students.

It is one thing if a lyric voice that has great strength undertakes a dramatic part. It is a different issue when a lyric voice that does not have the ability to produce great volume assumes a role that dramatically demands such volume. I such cases the CT will buckle and the singer’s naturally balance will be altered.

A very detailed list of intrinsic laryngeal musculature is included here and can be daunting. This is the list of muscular action I had hoped to include on the very first post of this blog which remains incomplete. I welcome questions about the musculature and relevant actions and how they interact with the basic vocalis-CT antagonism.

© 10/07/2008