There is a reason why I specify the Vocalis Muscle when I write about the TA muscle that thickens the vocal folds vertically. When most people speak about the TA, they are speaking about the Vocalis and its antagonistic function against or with the thinning of the vocal folds as resulted by CT (Crico-thyroid) contraction. In other words, the Vocalis muscle does not always shorten the vocal folds. The folds can be lengthened and thickened simultaneously to a degree. Too much thickening prevents the lengthening of the folds but appropriate thickening does not prevent the folds from being lengthened. All of this is of course dependent upon specific pitch. Low pitches of course will have thick and shorter fold posture and high pitches will have thin and long fold posture. The artistic use of the vocal folds in classical singing requires finer motor control. Indeed a paradoxical balance is necessary for peak efficiency. The folds must be appropriately thick and appropriately lengthened.
When the CT lengthens the folds it does not necessarily thin them out. But parallel to CT contraction is the contraction of the external TA (Vocalis is Internal TA). This muscle is the direct antagonist of the TA when it comes to fold thickness. Additionally, it brings the folds closer together since its contraction is slightly oblique, inward in the direction of the glottis. This is the most significant part of this discussion. The thinning and adductive effect of the External TA, which is complimentary and parallel to the lengthening effect of the CT, plays a significant role in final phonation-balance. Longer and thinner folds adduct more readily. Thicker and shorter folds, with little External TA action, require greater IA activity to fully adduct. Consequently, fully adducted heavy singing (too thick, too short posture) require a certain hyperactivity from the IAs which result in pressed phonation on higher pitches where the folds come together more closely because of External TA contraction.
It must not be forgotten that a full spectrum of overtones is necessary particularly for Second Formant Tracking (accessing head resonance: middle voice for women, high voice for men). A full spectrum of overtones requires greater fold mass and good closure. This is where the tight-rope act becomes necessary. The folds must be lengthy enough to benefit from the partial adduction provided by the External TA, such that the IA does not over-adduct. At the same time, the Vocalis must thicken the folds enough to provide the potential for a rich spectrum. Proper balance means that the folds are both thick enough and thin/lengthy enough. I love the paradoxical nature of this function.
Therefore, when we speak of a lean production, Voce Magra, we are not speaking about only thin vocal folds, but appropriately thin folds. This tenuous balance manifests in the ability to sing a full tone with unlimited dynamic variations. The ability to crescendo and diminuendo on one pitch, commonly but erroneously called messa di voce, depends on this precarious balance. Many singers are able to accomplish this in one part of the voice and not in another. Dynamic control of the voice is therefore not possible in a voice that is produced too thick or to thin.
I venture to conclude that the disappearance of the messa di voce and the authentic trill in top level singers of our times has a great deal to do with what I would like to coin Faching Inflation. A spinto singing Wagnerian repertoire will tend to thicken the voice to produce the desirable sound. Since modern Wagnerian singing seems to concentrate on loudness alone when it comes to vocal means, many lighter-voiced singers can get away with inappropriate thickening. Likewise, this generation of Nemorini and Adine in Egitto, (a slight variation on Mario del Monaco’s phrase, Nemorino in Egitto, describing an undervoiced Radamès) has produced a great number of inappropriately thickened voices that unfortunately do not last very long on the professional stage.
On a personal note, I am thankful once more for my 6 years with George Shirley, who made me aware of what I have called The Little Voice. This little voice, often called reinforced falsetto, is a modal production. Indeed a real voice! I call it little because it lacks the mass to produce a full spectrum of overtones, but on the other end it has appropriate length and closure. As I have learned to develop my high voice from this lighter coordination, I am beginning to experience the heavenly sensation of singing a high B or even C with a feeling of elasticity. The appropriate thickness of the upper register can only be achieved with the appropriate thinness of the lower. My most rewarding strides to date have been achieved when I produce an appropriately lean lower and middle voice. When this is achieved, the transition to the upper register feels natural and uneventful. Because the lower register is appropriately thin, the upper does not suffer excessive thinning as would happen from a sudden release of the Vocalis to the hyper-function of the CT. Instead a dynamic exchange of dominance between Vocalis and CT/External TA occurs. The contraction of the IA in such a case remains more or less constant with possible subtle variations. George Shirley convinced me in my early 20s that the ability to produce the little voice is a hallmark of healthy singing. Well Mr. Shirley, the hallmark of a great teacher is that you continue to learn from him even after leaving his side for many years. (Thank you, Sir and I miss you)!
Indeed as I conclude this post, I cannot help but to think of Jussi Björling, whose centennial anniversary was celebrated only a few days ago. In my estimation, no male singer achieved this paradoxical balance more completely than Jussi at his best. Look for the Björling retrospective here in a few days, called appropriately: Belt it Like Björling!