“One finds no universal agreement upon how many different registers there are or what to call them, but if there is any consensus it is that the quality of notes in the lowest part of the range is typically different from those of the highest part of the range, at least in the voice of a beginner.” —Stephen F. Austin1
“Mixed Register. Refers to a balance of TA/mode 1 and CT/mode 2 registration in singing. While the vocal folds are ultimately more engaged in one mode (register) than the other, modification of the acoustic space in the zona di passaggio can give the singer the feeling—and listener the perception—of a third (“mixed”) register. The mixed register concept is controversial among vocal pedagogues, many of whom do not acknowledge it as a true register. The term is most frequently encountered when discussing the middle range of the singer and in reference to the transition that occurs between chest (TA/mode 1) and head (CT/mode 2) voice. In this sense, mixed register refers to the gradual and subtle shifting between registers to eliminate abruptness and give the illusion of a smooth and seamless tone quality throughout the range of the singer. Also called coordinated register.” —Matthew Hoch2
The terminology we use to describe vocal registration can be a source of controversy and confusion. There is increasing agreement among vocologists regarding the mechanisms behind registration, but research has yet to yield consensus about how to conceptualize and navigate vocal registers. Teachers employed terms like “chest voice” and “falsetto” long before we developed an anatomical understanding of heavy and light vocal production. Now that we have begun to, it turns out that traditional terminology does not precisely align with scientific descriptors.
The aim of this column is not to provide a detailed analysis of the physiology of registration but rather to offer an introduction to the basics of how it works, clarify some key vocabulary, and offer some exercises for improving registration skills.
An Agonist/Antagonist Relationship
The laryngeal muscles governing registration are the thyroarytenoid (TA), which forms the body of the vocal folds, and the cricothyroid (CT), which lengthens and tenses the vocal folds.
When the TA is the more dominant of the two muscles, it results in the weightier vocal production often referred to as chest voice. When the CT dominates, the result is what is sometimes called head voice or falsetto. The combined activity of these two muscles varies the length and width of the vocal folds, impacting pitch and registration.
Muscles work together to generate and stabilize movement. Your hamstrings bend (or flex) your knee; your quadriceps extend your knee. They have an agonist/antagonist relationship, collaborating to control the rate of movement and degree of force production around your knee. Your hamstrings accelerate knee flexion while the quadriceps decelerate knee flexion, while the opposite is true for knee extension. Bend your knee in a variety of positions and at different speeds and observe its movement when walking or running. Because you have a great deal of experience flexing and extending your knees, these movements are smooth and easy to control.
Your TA and CT muscles share a relationship similar to that between the hamstrings and quadriceps. The TA creates thickness by shortening and stiffening the vocal folds, while the CT opposes its movements to create narrowness and length. They accelerate and decelerate the various movements of the vocal folds in a way that can potentially yield smooth, stable, and balanced movement.
Achieving Balance
Sirens are the most effective exercises I know for diagnosing registration issues as well as for establishing balance. Perform the following exercises with a simple, steady release of your breath, keeping your throat as relaxed as possible.
Descending
Starting on a pitch that is high enough for you to onset in what you consider head voice or falsetto, perform a relaxed descending siren to the bottom of your range, using either a hum or your favorite vowel.
Are you able to slide all the way down with consistent quality and focus or are there sudden changes in the weight and timbre of your voice?
Is the siren continuous from top to bottom or is there an interval where your voice skips?
On your onset, your CT is dominant, but the TA must gradually become more active as you descend in order to maintain consistent timbre and healthy vocal fold closure.
If when you arrive at the bottom of the siren your tone is relatively weak and unfocused, this may be due to inadequate engagement of the TA. Encourage weightier registration at the bottom even if at first you are not able to transition to it smoothly.
If your voice suddenly breaks into heavier registration, this may indicate a need to maintain continuous engagement of the CT and develop more integrated coordination with the TA. See if you can keep the overall registration lighter lower into the descent and allow the break to occur later.
Ascending
Beginning at the bottom of your range with a quality of registration you would associate with chest voice, siren up as far as you comfortably can.
Do you ascend into head voice territory or do you top out around the bottom of your passaggio?
Are you able to slide up with consistent quality, focus, and comfort or are there sudden changes in the weight, timbre, and freedom of your voice?
Is the siren continuous from bottom to top or is there an interval where your voice skips?
On your onset, your TA is dominant; as you ascend, it must gradually give over control to the CT in order to maintain consistent timbre and avoid excessive vocal fold adduction.
If you find that your throat tightens as you ascend and you cannot move comfortably into the passaggio, it may mean that you are maintaining a similar degree of tension in the TA throughout the ascent rather than gradually relaxing it and allowing the CT to take over. Encourage lighter registration toward the top even if at first you are not able to transition to it smoothly.
If your voice suddenly breaks into lighter registration or skips an interval on the ascent, this may indicate a need to engage your CT more actively right from the beginning of the siren so that it partners well with the TA throughout. Allow the overall registration to become lighter lower in the ascent and allow any break to occur earlier.
While singers may instinctively strive to avoid the startling sound and sensation of a break in the voice, eliciting a “crack” in both directions is a useful way to explore movement between registers and begin to equalize strength between the muscles governing this movement. Stephen Austin points out that this technique dates back to the teaching of Manuel García in the 19th century. García encouraged “beginning a tone in one register and without stopping the air flow, allowing the tone to ‘flip’ into an adjacent register. Register ‘breaking’ depends upon the fact that the ranges of adjacent registers overlap and a large number of pitches can be sung with one of several laryngeal adjustments, or registers. In García’s method, these were ‘first studies.’” 3
In his book Vocology: The Science and Practice of Voice Habilitation, pioneering voice scientist Ingo Titze explains that “Voice quality stays relatively constant in certain plateaus where pitch, loudness, and vowel have a minor effect on vocal fold vibration. Then there is a sudden change known as a register transition, or passaggio in Italian. The best exercise for learning to appreciate vocal registration is the yodel.”4
Bel Canto masters and modern scientists agree that exposing registration imbalances is an essential step on the path to resolving them.
The Registration Continuum
“Lower register voice qualities are produced when both the thyroarytenoid and the cricothyroid muscles are simultaneously contracted (primary shorteners and lengtheners, respectively), but the thyroarytenoids are more prominently contracted than the cricothyroids. Various agonist-antagonist contractions of the two muscles result in a range of stabilizations in vocal fold length, thickness, and tautness . . . Upper register voice qualities are produced when both the thyroarytenoid (primary shortener) and the cricothyroid (primary lengthener) muscles are simultaneously contracted, but the cricothyroids are more prominently contracted than the thyroarytenoids.” —Leon Thurman5
While I have used the terms “chest voice” and “head voice” throughout this column, I personally think of, experience, and teach registration as a continuum. The fact that the authors of the above quote describe registration as a varying balance between simultaneously contracted thyroarytenoid and cricothyroid muscles yet continue to delineate between lower and upper register voice qualities attests to how firmly this language of register separation is entrenched in our shared vocabulary.
Most any note you sing is not restricted to a specific optimal weight but can rather be produced within a range of heaviness or lightness depending upon the musical style, desired expressive color or dynamic level, whether it is approached from above or below, and other factors. Registration is a skill that can be cultivated. A classical singer who masters registration will enjoy not only seamless continuity of timbre from high to low but also a fantastic palate of expressive possibilities throughout their range. A musical theatre performer who masters registration will be able to move between belt and legit singing without stress.
I understand why many find it practical to conceptualize distinct chest and head registers, develop them separately, and work on blending them together. Most singers begin their training with a noticeable imbalance between their TA and CT muscles—some need considerable instruction and practice before they are even able to reliably produce heavy registration or falsetto, while others develop a “hole” in their middle voice as the result of failing to develop synergy in the muscles of registration. But with the development of good coordination, the necessity of distinguishing between registers gradually disappears. Navigating the weight of your voice can become as easy as navigating the weight of your body as your hamstrings and quadriceps work together to walk you down the street.
It would be an oversimplification to suggest, however, that registration is as easy as walking down the street. Research is ongoing, and there remain disagreements among voice teachers and vocologists about how registration works and how imbalances can best be alleviated.
While I have discussed the two significant muscles that control registration at the level of the vocal folds, there are many other factors that can influence registration, including vowel definition, breath management, and alignment. However, I find that viewing registration as a continuum of muscular coordination provides a useful inroad for understanding this complex process and moving past the somewhat limiting vocabulary traditionally used to describe it.
Endnotes
1. Stephen F. Austin, “Register Unification—Give Me a Break!” Journal of Singing (Nov/Dec 2004), 200.
2. Matthew Hoch, A Dictionary for the Modern Singer (Baltimore, MD: Rowman & Littlefield Publishers, 2014), 113.
3. Austin, 200.
4. Ingo Titze and Katherine Verdolini Abbott, Vocology: The Science and Practice of Voice Habilitation (Salt Lake City, UT: National Center for Voice and Speech, 2012), 271.
5. Leon Thurman, et al, “Addressing Vocal Register Discrepancies: An Alternative, Science-Based Theory of Register Phenomena.” (Second International Conference of The Physiology and Acoustics of Singing, National Center for Voice and Speech, 6 – 9 October 2004, Denver, Colorado).
