Pierrot mit der Guitarre by Honoré Daumier
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Have you ever played an instrument you could see? Did seeing it help you learn how to play it? Vocalists are at a huge disadvantage because they never get to see the instrument they are playing. This can lead to frustration, built up mythology and inefficient methods for creating the sounds we want to produce.
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While none of the muscles inside the larynx can be felt or directly controlled, having a clear concept of how each body part works gives vocal learners and instructors direct and clear guidance when devising methods to achieve their vocal goals.
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where is the larynx?
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The larynx sits at the top of the trachea.
The trachea , or the windpipe, is a tube made of cartilage that allows air to travel to and from the lungs. The vocal folds, also called vocal cords, sit inside the larynx. Their primary function is to protect the airway and make sure nothing unwanted goes down the trachea in the lungs. |
what is the larynx made of?
"Stretch"
Crichothyroid (CT)
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"Thicken"
Thyroarytenoid (TA)
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"Open"
Posterior Crichoarytenoid (PCA)
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"Bring Together"
Lateral Crichoarytenoid (LCA)
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"Bring Together"
Interarytenoid (IA)
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Of the five images above, the first view point looks at the side of the neck from the right side. The other four images look at the vocal folds from above. The lower three images show only the vocal ligament, not the thyroarytenoid muscle, to avoid confusion about which muscle is being featured.
The three cartilages of the vocal folds. The muscles are named based on which cartilages they touch.
The larynx is made of 3 main cartilages (one is paired), 1 bone, and 5 muscle groups.
The vocal folds are attached to the cartilages. The 2 largest cartilages (crichoid and thyroid) can rock and glide, one on top of the other, to change the vocal folds' shape. The other paired cartilage (arytenoid) has significant mobility to help determine how the vocal folds align and vibrate.
There are muscles that help bring the vocal folds together.
The vocal folds come together to
a) keep unwanted particles out of the lungs
b) stop airflow
c) phonate (i.e. make sound, speaking, singing)
There are muscles that open the vocal folds.
The vocal folds open to
a) let air in (inhalation/inspiration)
b) let air out (exhalation/expiration)
The opening and bring together muscles are antagonistic (when one activates, the other has to release). However, except in extreme cases, the opening and bring together muscles are activated simultaneously. Their trade-off happens rapidly in a back-and-forth manner, adjusting as needed in response to breath and acoustic variables, and to our desired outcome as encouraged by the brain.
There are muscles that stretch and thin the vocal folds
In phonation, when the vocal folds stretch they
a) change the pitch created by the vocal folds
b) increase tension on the vocal folds to create higher pitches
There are muscles that shorten and thicken the vocal folds
In phonation, when the vocal folds thicken they
a) contribute to a 'heavier' sound
b) contribute to a 'louder' sound
c) decrease tension on the vocal folds to create lower pitches
The stretching and thickening muscles are antagonistic (when one activates, the other has to release). However, except in extreme cases, both the stretching and thickening muscles are activated simultaneously. Their trade-off happens rapidly in a back-and-forth manner. This article by Soren Lowell and Brad Story explains in greater detail the uniqueness of these muscle's antagonism based on simulated trials.
Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
The vocal folds are attached to the cartilages. The 2 largest cartilages (crichoid and thyroid) can rock and glide, one on top of the other, to change the vocal folds' shape. The other paired cartilage (arytenoid) has significant mobility to help determine how the vocal folds align and vibrate.
There are muscles that help bring the vocal folds together.
The vocal folds come together to
a) keep unwanted particles out of the lungs
b) stop airflow
c) phonate (i.e. make sound, speaking, singing)
There are muscles that open the vocal folds.
The vocal folds open to
a) let air in (inhalation/inspiration)
b) let air out (exhalation/expiration)
The opening and bring together muscles are antagonistic (when one activates, the other has to release). However, except in extreme cases, the opening and bring together muscles are activated simultaneously. Their trade-off happens rapidly in a back-and-forth manner, adjusting as needed in response to breath and acoustic variables, and to our desired outcome as encouraged by the brain.
There are muscles that stretch and thin the vocal folds
In phonation, when the vocal folds stretch they
a) change the pitch created by the vocal folds
b) increase tension on the vocal folds to create higher pitches
There are muscles that shorten and thicken the vocal folds
In phonation, when the vocal folds thicken they
a) contribute to a 'heavier' sound
b) contribute to a 'louder' sound
c) decrease tension on the vocal folds to create lower pitches
The stretching and thickening muscles are antagonistic (when one activates, the other has to release). However, except in extreme cases, both the stretching and thickening muscles are activated simultaneously. Their trade-off happens rapidly in a back-and-forth manner. This article by Soren Lowell and Brad Story explains in greater detail the uniqueness of these muscle's antagonism based on simulated trials.
Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
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Visit the Interactive Larynx site for an in-depth look at how each laryngeal muscle group moves
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What's the larynx's purpose in the body?
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Because protecting the airway is such an important job, the body spared no fineries in this part of biology. That's why there are multiple muscles that do the same task: bringing the vocal folds together. In case one set of muscles fails, another set can take over.
The vocal folds will also come together in tasks like lifting heavy objects, defecating, and child birth. If air is not allowed to escape past the larynx, pressure will build in the torso offering more resistance for a difficult task. This is why you may hear a grunt after a heavy lift. This is the air is escaping in a large burst after being held below the vocal folds during the task. The secondary function of the larynx is to create sound. Muscles in the larynx bring the vocal folds together which interrupts air escaping the lungs. The number of times they interrupt the airflow per second creates the pitch. See our page on How We Make Sound for more information.
Note that the muscles of the larynx put the vocal folds into position for vibration. They do not vibrate themselves to create the pitch. |
View of larynx looking down the throat into the trachea
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HOw does the larynx contribute to the sound being made?
The Thickening Muscle (The thyroarytenoid/TA muscle)
The thickening muscle (TA) makes up the bulk of the vocal folds themselves. When it activates, the TA shortens and thickens the vocal folds. When a larger bulk of the folds participates in vibration, more harmonic information gets released from the vocal folds.
This affects the quality of the sound.
For lower notes, the folds vibrate slower and therefore can remain shorter and thicker. For higher notes, the folds vibrate faster. As the folds stretch, the thickening (TA) muscle may need to play a different role. For higher notes, the folds can move to just their edges to vibrate. In this case, the thickening (TA) muscle doesn't actually touch any longer. Instead, it's function becomes one of regulating relative stiffness so the cover of the folds can vibrate. Even though the thickening (TA) muscle isn't touching for vibration purposes, it is still active when the folds are on their edges, just functioning differently.
The TA thickening muscle also makes up the body of the vocal folds. It highly influences the stiffness of the folds. Stiffness is a technical term here, not a derogatory one. Stiffness in the thickening (TA) helps keep the folds in vibration. The amount of vibration the body and cover of the folds experience impacts the quality of the sound as well. A stiffer thickening (TA) muscle will vibrate less. One of the goals of coordination across the vocal fold mechanism can be to allow for less TA stiffness, therefore more vibration, by allowing other aspects of the vocal mechanism to keep the vocal folds in vibration.
The transition from the thickening (TA) muscle touching to being on its edges is likely where we get language like:
"let go as you get higher", "don't push the top note", "turn it over, transition early", "don’t bring up the weight"
The thickening muscle (TA) makes up the bulk of the vocal folds themselves. When it activates, the TA shortens and thickens the vocal folds. When a larger bulk of the folds participates in vibration, more harmonic information gets released from the vocal folds.
This affects the quality of the sound.
For lower notes, the folds vibrate slower and therefore can remain shorter and thicker. For higher notes, the folds vibrate faster. As the folds stretch, the thickening (TA) muscle may need to play a different role. For higher notes, the folds can move to just their edges to vibrate. In this case, the thickening (TA) muscle doesn't actually touch any longer. Instead, it's function becomes one of regulating relative stiffness so the cover of the folds can vibrate. Even though the thickening (TA) muscle isn't touching for vibration purposes, it is still active when the folds are on their edges, just functioning differently.
The TA thickening muscle also makes up the body of the vocal folds. It highly influences the stiffness of the folds. Stiffness is a technical term here, not a derogatory one. Stiffness in the thickening (TA) helps keep the folds in vibration. The amount of vibration the body and cover of the folds experience impacts the quality of the sound as well. A stiffer thickening (TA) muscle will vibrate less. One of the goals of coordination across the vocal fold mechanism can be to allow for less TA stiffness, therefore more vibration, by allowing other aspects of the vocal mechanism to keep the vocal folds in vibration.
The transition from the thickening (TA) muscle touching to being on its edges is likely where we get language like:
"let go as you get higher", "don't push the top note", "turn it over, transition early", "don’t bring up the weight"
 Top view of vocal folds stretching, looking down the throat into the trachea
The Stretching Muscle (The crichothyroid/CT muscle)
The stretchy (CT) muscle connects the thyroid cartilage that houses the vocal folds with the more stable crichoid cartilage one below it. When the stretchy (CT) muscle contracts, the thyroid cartilage can rock and glide on top of the crichoid cartilage. This rocking and gliding results in the vocal folds lengthening, thinning, and stretching. The amount of stretch that occurs helps change the pitch being produced. For the vast majority of people's vocal ranges (even down into the lower part of their range), the stretchy (CT) muscle engages more dominantly than the others*. This is particularly important when considering the antagonism with the stretching (CT) and thickening (TA) muscles. Because most people speak in a limited and low pitch range, they may not activate their stretchy (CT) muscle as often. Prioritizing the stretchy (CT) muscle as dominant in the overall coordination can be difficult for new singers who use it less actively for speech. * See Darcy M. Hull's Thyroarytenoid and cricothyroid muscular activity in vocal register control for more on this. |
Side view of the CT muscle stretching the vocal folds
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Trade Off Between Muscles
The heavy thickening muscle (TA) and the stretching thinning muscle (CT) are considered antagonistic. As one increases activity, the other must decrease. This happens rapidly and in an ongoing way. A person can't feel or even hear the tradeoff.
When people experience a "crack" or "break" in the voice, it may be a result of the shortening/thickening muscle and the stretching/thinning muscle having an unbalanced trade off in muscle coordination.
At range extremes, the capacity for this particular antagonism diminishes, leaving other muscles to coordinate the vocal folds so that they can continue to vibrate.*
Where the other muscles are concerned, there's more to the story. The lateral crichoarytenoid and posterior crichoarytenoid muscles are also antagonistic. Further still, the ways in which all five of the intrinsic muscle groups coordinate represents a vast web of potential alignment. Each muscle group has an impact on varied aspects of voicing including fundamental frequency (pitch), vibration patterns, and onsets/releases. To add a few more variables, extrinsic muscles that attach to the larynx also have a role to play in determining these variables. This complexity plays a large role in every person having a unique vocal signature. When it comes to the vocal folds, how coordination occurs makes all the difference. The challenge with tracking coordination lies in not being able to feel or touch or directly track the sea of variables at play.
*Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
Yin, Jun and Zhaoyan Zhang. Interaction between the thyroarytenoid and lateral crichoarytenoid muscles in the control of vocal fold adduction and Eigenfrequencies. National Library of Medicine, September, 2014.
The heavy thickening muscle (TA) and the stretching thinning muscle (CT) are considered antagonistic. As one increases activity, the other must decrease. This happens rapidly and in an ongoing way. A person can't feel or even hear the tradeoff.
When people experience a "crack" or "break" in the voice, it may be a result of the shortening/thickening muscle and the stretching/thinning muscle having an unbalanced trade off in muscle coordination.
At range extremes, the capacity for this particular antagonism diminishes, leaving other muscles to coordinate the vocal folds so that they can continue to vibrate.*
Where the other muscles are concerned, there's more to the story. The lateral crichoarytenoid and posterior crichoarytenoid muscles are also antagonistic. Further still, the ways in which all five of the intrinsic muscle groups coordinate represents a vast web of potential alignment. Each muscle group has an impact on varied aspects of voicing including fundamental frequency (pitch), vibration patterns, and onsets/releases. To add a few more variables, extrinsic muscles that attach to the larynx also have a role to play in determining these variables. This complexity plays a large role in every person having a unique vocal signature. When it comes to the vocal folds, how coordination occurs makes all the difference. The challenge with tracking coordination lies in not being able to feel or touch or directly track the sea of variables at play.
*Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
Yin, Jun and Zhaoyan Zhang. Interaction between the thyroarytenoid and lateral crichoarytenoid muscles in the control of vocal fold adduction and Eigenfrequencies. National Library of Medicine, September, 2014.
These are some of the main variables that influence phonation. Each of them is highly complex, with countless variables within their makeup. With all of the variables at play during phonation, consider how many different ways there are to sing a middle C. Even when two people sound similar, the exact coordination pattern they are using will be different in some ways.
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The vocal folds themselves are a highly specialized combination of muscle, ligament, and mucosa. The vocal ligament is of particular interest, because it is able to bear significant amounts of pressure. This is one reason why the human vocal folds, which are tiny in comparison to other instruments, are able to phonate over such a large range of notes.
Scientifically, there are two ways to understand the layers of the vocal folds. In the top graphic, we think of the vocal folds as three layers: muscle (TA), ligament, and muscosa. The mucosa is specially calibrated to always vibrate when the vocal folds are active. The muscle can have varying degrees of stiffness, and therefore, varying degrees of vibration. In the lower graphic, we consider the ligament and mucosa as parts of the cover. The cover always vibrates when the vocal folds are active. The vibration of the body is determined by the stiffness of the TA muscle. The ways in which the body and cover vibrate have more direct influence on the sound a voice makes than the muscles do. How the muscles coordinate plays a large part in determining how the body and cover vibrate. |
Language around laryngeal muscle interaction
When we begin to understand laryngeal muscle function, we create opportunities to speak with greater clarity about the voice. Traditional voice terminology uses terms like "head voice" and "chest voice" to describe so-called vocal registers. The primary challenge to this kind of terminology lies in its over simplicity. Binaries used to describe radical complication struggle to describe with accuracy.
Because of the binary structure of "head and chest", most of what defines the difference between them focuses on a singular event in the voice known by various labels like "break, crack, flip, etc." Everyone who has tried to glide across their range from low to high has felt this event. Choosing to accept the complication present when voicing leads to new ways of hearing and experiencing the voice. This newness requires new language that relates to complexity and coordination beyond binary metaphors like head/chest, bright/dark, and front/back. (read more on this topic our Vocal Registers? page)
There are many ways of discussing the complexities related to the vocal folds. They include, for example, discussing the muscle interaction itself. Although we can't feel the muscles directly, researchers are starting to uncover ways in which the muscles interact with one another in their complex dance. This information can help us imagine what other options might be possible, and to seek out sounds that represent what we understand to be the new combinations. For example, Brad Story and Ingo Titze, and Yin Jun and Zhaoyan Zhang have demonstrated in separate studies that the CT and TA muscles antagonism ceases to function at a certain point in a person's range, but sound can still be made beyond that point. New understanding of the interaction of the LCA and the TA demonstrate ways in which the vocal folds can continue to vibrate even when the CT and TA aren't as active in their antagonistic dance. Pulse sounds reflect one such phonation. Therefore, to learn to apply a pulse sound to other aspects of voicing could encourage more LCA interaction in the voice coordination cocktail.
We've found that when we allow more metaphoric/less specific language, especially those based on binaries, to recede from the vocabulary and be replaced by specific language that attempts to more accurately define complexity, learning increases at a rapid pace. Future confusion tends to be replaced by exciting questions. Of course, when performing, a person can't be thinking of muscle group interactions let alone all of the complexity involved in phonation. The process of learning to explore sound through measurable knowledge, describe experience, and then release the knowledge you have into the magic of performance remains part of the art of voice learning. Giving language to complexity affords a vocalist more potential paths to discovering their desired targets, and recalling them when they want.
Here are some of the events and language possible for some of the variables present in voicing
Muscle mass variations
The amount of the vocal folds that touch during vocal fold vibration impacts the energy in the harmonics produced. When more muscle mass touches during vibration, all harmonics have more energy, when less touches, all harmonics have less energy.
We like to use our hands to demonstrate this, showing the palms and fingers in vibration for the full muscle mass, and fewer fingers for less muscle mass, flipping to the first fingers alone for a ligament-dominant position.
When the thickening muscles (TA) touch during vibration, they assume the bulk of the strain on the vocal folds. When the thickening muscles (TA) do not touch in vibration, that is, when the folds are on their edges, the vocal ligament assumes the bulk of the strain on the vocal folds.
Three important elements to remember:
1) The stretchy (CT) and thickening (TA) muscles are most often both in use. They are in a constant, rapidly-changing dance with one another. There isn't a moment when one stops and the other starts (except in certain range extremes). There is, however, a moment when the thickening (TA) muscles no longer touch one another, and therefore are no longer in vibration. Moments like this one require a high degree of stiffness from the thickening (TA) muscle.
2) There are countless variations of how the thickening muscle (TA) can be in vibration. When the full muscle mass touches during vocal fold vibration, for example, vocalists create the greatest amount of harmonic output. If that outcome is desirable, knowing how it feels and sounds will be important for recreating it. The same can be said of any muscle mass configuration.
3) Without the most sophisticated equipment, a vocalist can't be sure of exactly how much muscle mass is in vibration. We use our ears and understanding of the instrument to get a general idea of muscle use. The brain's need to narrow potential options often leads people to create two or three metaphors to describe what is actually endless varitety. Finding ways to create clarity in your thinking, and measurable repetition can be freeing.
Opening and Bring Together Muscles
The interplay between the opening (PCA) and bring together (LCA and IA) muscles can influence sound output in significant ways. New research has shown that they have a higher degree of interaction with the thickening (TA) and stretchy (CT) muscles than previously understood. It is possible that when the coordination of variables leads to a greater amount of pressure on the vocal folds to remain in vibration, the thickening (TA) muscle often increases its stiffness. The vibration of the body of the vocal folds thereby diminishes. This may be what researchers like Johan Sundberg refer to as "pressed" phonation. In such instances, more active bring together (LCA and IA) muscles might alleviate some of the stress on the thickening (TA) muscle, leading to more body vibration. This has been a documented outcome of pulse tone vibration. Equally, the bring together (LCA and IA) muscles can interact in multiple ways that increase high harmonic energy in the sound above 4,000Hz. The result can be what Sundberg calls "breathy" phonation. All of these are viable phonation options. In some instances they might be valuable, in others, less valuable. Understanding that the opening (PCA) and bring together (LCA and IA) muscles play important, integrated roles in phonation leads to the next question of how do we begin to hear the result of their coordination. Exploring these questions can also lead us away from all encompassing terms like Sundberg's "flow phonation," that may as well say "good sound" for all that it offers in terms of clarity.
Sundberg, Johan. The Science of the singing Voice. Northern Illinois University press, 1987, pg 79-85.
Vibration and Stiffness
Stiffness is a measurable variable related to the body of the vocal folds, which is also the thickening (TA) muscle. A high degree of stiffness means that the thickening (TA) muscle can not vibrate as much. Conversely, less stiffness means more body vibration. The amount of vibration that the body and cover of the vocal folds maintain contributes to ways that we hear the sound. More vibration during non-pulsed phonation may contribute to a less harmonically complicated sound. When the vocal folds are on their edges, and ligament dominant, the thickening (TA) muscle remains more stiff. During pulsed phonation, the thickening (TA) muscle has a low degree of stiffness. How we interpret the sonic result of these variables is open for discussion. Learning to hear the result of them can lead to clearer choices.
Maximum Flow Declination Rate
How quickly the vocal folds come together adds another important element to the overall discussion. The scientific measurement for this element is the "maximum flow declination rate." Simply put, it means the rate at which the flow of air from the beneath the vocal folds stops. For simple shorthand, you can refer to it as the "closing rate". Remember that each time the vocal folds are in full contact, the air flow ceases for that moment. This "full closure" moment is essential for creating sound. How quickly that air flow cessation occurs influences energy in the harmonic output. If the folds come together very quickly, all of the harmonics have increased energy. If the folds come together more slowly, the harmonics have less energy. Hearing the maximum flow declination rate (MFDR or "closing rate") as an unique contribution to sound can be difficult. Like laryngeal muscle interaction, it's impossible to assess specifically without sophisticated equipment. Software like VoxInSilico and Voce Vista's EGG capacity create distinct visual assessments to measure the MFDR "closing rate." Being aware of its important contribution, however, can open the ears to new variables in the overall sound, and lead to new language choices. Acoustic choices like increased "twang" can lead to increased MFDR (see Acoustic Strategies for more).
MFDR measures are an important aspect of the research that Lowell and Story explored: Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
Inertance
Inertance describes the mathematical result of the difference between breath pressure from below the vocal folds and acoustic back pressure from above the vocal folds.
This variable plays a significant role in how the vocal fold muscles can coordinate. When breath pressure exceeds acoustic back pressure, the vocal fold muscles have fewer coordination options in order to keep the vocal folds in vibration. Understanding acoustic strategies that increase inertance can lead to flexibility and power options in vocal choices. For more on inertance, see our Acoustic Strategies page, scroll down to "inertance."
Extrinsic muscles
There are multiple muscles outside of the larynx that attach to the larynx in some way. These muscles have been shown in studies to have influence on voicing, even including on fundamental frequency change. Though less influential in the full coordination than the intrinsic muscles, they still play a role. When they play an outsized role in phonation, challenges can occur. Psychologically, people often revert to larger muscles when attempting new tasks or under stress. Phonating in new ways can often begin by employing extrinsic muscles in ways that destabilizes the target sound. Learning to check in with these muscles, to explore body/mind integration, and to employ techniques like massage can lead to helpful integration of these muscles into the overall coordination.
When we begin to understand laryngeal muscle function, we create opportunities to speak with greater clarity about the voice. Traditional voice terminology uses terms like "head voice" and "chest voice" to describe so-called vocal registers. The primary challenge to this kind of terminology lies in its over simplicity. Binaries used to describe radical complication struggle to describe with accuracy.
Because of the binary structure of "head and chest", most of what defines the difference between them focuses on a singular event in the voice known by various labels like "break, crack, flip, etc." Everyone who has tried to glide across their range from low to high has felt this event. Choosing to accept the complication present when voicing leads to new ways of hearing and experiencing the voice. This newness requires new language that relates to complexity and coordination beyond binary metaphors like head/chest, bright/dark, and front/back. (read more on this topic our Vocal Registers? page)
There are many ways of discussing the complexities related to the vocal folds. They include, for example, discussing the muscle interaction itself. Although we can't feel the muscles directly, researchers are starting to uncover ways in which the muscles interact with one another in their complex dance. This information can help us imagine what other options might be possible, and to seek out sounds that represent what we understand to be the new combinations. For example, Brad Story and Ingo Titze, and Yin Jun and Zhaoyan Zhang have demonstrated in separate studies that the CT and TA muscles antagonism ceases to function at a certain point in a person's range, but sound can still be made beyond that point. New understanding of the interaction of the LCA and the TA demonstrate ways in which the vocal folds can continue to vibrate even when the CT and TA aren't as active in their antagonistic dance. Pulse sounds reflect one such phonation. Therefore, to learn to apply a pulse sound to other aspects of voicing could encourage more LCA interaction in the voice coordination cocktail.
We've found that when we allow more metaphoric/less specific language, especially those based on binaries, to recede from the vocabulary and be replaced by specific language that attempts to more accurately define complexity, learning increases at a rapid pace. Future confusion tends to be replaced by exciting questions. Of course, when performing, a person can't be thinking of muscle group interactions let alone all of the complexity involved in phonation. The process of learning to explore sound through measurable knowledge, describe experience, and then release the knowledge you have into the magic of performance remains part of the art of voice learning. Giving language to complexity affords a vocalist more potential paths to discovering their desired targets, and recalling them when they want.
Here are some of the events and language possible for some of the variables present in voicing
Muscle mass variations
The amount of the vocal folds that touch during vocal fold vibration impacts the energy in the harmonics produced. When more muscle mass touches during vibration, all harmonics have more energy, when less touches, all harmonics have less energy.
We like to use our hands to demonstrate this, showing the palms and fingers in vibration for the full muscle mass, and fewer fingers for less muscle mass, flipping to the first fingers alone for a ligament-dominant position.
When the thickening muscles (TA) touch during vibration, they assume the bulk of the strain on the vocal folds. When the thickening muscles (TA) do not touch in vibration, that is, when the folds are on their edges, the vocal ligament assumes the bulk of the strain on the vocal folds.
Three important elements to remember:
1) The stretchy (CT) and thickening (TA) muscles are most often both in use. They are in a constant, rapidly-changing dance with one another. There isn't a moment when one stops and the other starts (except in certain range extremes). There is, however, a moment when the thickening (TA) muscles no longer touch one another, and therefore are no longer in vibration. Moments like this one require a high degree of stiffness from the thickening (TA) muscle.
2) There are countless variations of how the thickening muscle (TA) can be in vibration. When the full muscle mass touches during vocal fold vibration, for example, vocalists create the greatest amount of harmonic output. If that outcome is desirable, knowing how it feels and sounds will be important for recreating it. The same can be said of any muscle mass configuration.
3) Without the most sophisticated equipment, a vocalist can't be sure of exactly how much muscle mass is in vibration. We use our ears and understanding of the instrument to get a general idea of muscle use. The brain's need to narrow potential options often leads people to create two or three metaphors to describe what is actually endless varitety. Finding ways to create clarity in your thinking, and measurable repetition can be freeing.
Opening and Bring Together Muscles
The interplay between the opening (PCA) and bring together (LCA and IA) muscles can influence sound output in significant ways. New research has shown that they have a higher degree of interaction with the thickening (TA) and stretchy (CT) muscles than previously understood. It is possible that when the coordination of variables leads to a greater amount of pressure on the vocal folds to remain in vibration, the thickening (TA) muscle often increases its stiffness. The vibration of the body of the vocal folds thereby diminishes. This may be what researchers like Johan Sundberg refer to as "pressed" phonation. In such instances, more active bring together (LCA and IA) muscles might alleviate some of the stress on the thickening (TA) muscle, leading to more body vibration. This has been a documented outcome of pulse tone vibration. Equally, the bring together (LCA and IA) muscles can interact in multiple ways that increase high harmonic energy in the sound above 4,000Hz. The result can be what Sundberg calls "breathy" phonation. All of these are viable phonation options. In some instances they might be valuable, in others, less valuable. Understanding that the opening (PCA) and bring together (LCA and IA) muscles play important, integrated roles in phonation leads to the next question of how do we begin to hear the result of their coordination. Exploring these questions can also lead us away from all encompassing terms like Sundberg's "flow phonation," that may as well say "good sound" for all that it offers in terms of clarity.
Sundberg, Johan. The Science of the singing Voice. Northern Illinois University press, 1987, pg 79-85.
Vibration and Stiffness
Stiffness is a measurable variable related to the body of the vocal folds, which is also the thickening (TA) muscle. A high degree of stiffness means that the thickening (TA) muscle can not vibrate as much. Conversely, less stiffness means more body vibration. The amount of vibration that the body and cover of the vocal folds maintain contributes to ways that we hear the sound. More vibration during non-pulsed phonation may contribute to a less harmonically complicated sound. When the vocal folds are on their edges, and ligament dominant, the thickening (TA) muscle remains more stiff. During pulsed phonation, the thickening (TA) muscle has a low degree of stiffness. How we interpret the sonic result of these variables is open for discussion. Learning to hear the result of them can lead to clearer choices.
Maximum Flow Declination Rate
How quickly the vocal folds come together adds another important element to the overall discussion. The scientific measurement for this element is the "maximum flow declination rate." Simply put, it means the rate at which the flow of air from the beneath the vocal folds stops. For simple shorthand, you can refer to it as the "closing rate". Remember that each time the vocal folds are in full contact, the air flow ceases for that moment. This "full closure" moment is essential for creating sound. How quickly that air flow cessation occurs influences energy in the harmonic output. If the folds come together very quickly, all of the harmonics have increased energy. If the folds come together more slowly, the harmonics have less energy. Hearing the maximum flow declination rate (MFDR or "closing rate") as an unique contribution to sound can be difficult. Like laryngeal muscle interaction, it's impossible to assess specifically without sophisticated equipment. Software like VoxInSilico and Voce Vista's EGG capacity create distinct visual assessments to measure the MFDR "closing rate." Being aware of its important contribution, however, can open the ears to new variables in the overall sound, and lead to new language choices. Acoustic choices like increased "twang" can lead to increased MFDR (see Acoustic Strategies for more).
MFDR measures are an important aspect of the research that Lowell and Story explored: Lowell, Soren Y. and Brad Story. Simulated effects of cricothyroid and thyroarytenoid muscle activation on adult-male vocal fold vibration. Journal of the Acoustic Society of America. April, 2006, pages 386-397.
Inertance
Inertance describes the mathematical result of the difference between breath pressure from below the vocal folds and acoustic back pressure from above the vocal folds.
This variable plays a significant role in how the vocal fold muscles can coordinate. When breath pressure exceeds acoustic back pressure, the vocal fold muscles have fewer coordination options in order to keep the vocal folds in vibration. Understanding acoustic strategies that increase inertance can lead to flexibility and power options in vocal choices. For more on inertance, see our Acoustic Strategies page, scroll down to "inertance."
Extrinsic muscles
There are multiple muscles outside of the larynx that attach to the larynx in some way. These muscles have been shown in studies to have influence on voicing, even including on fundamental frequency change. Though less influential in the full coordination than the intrinsic muscles, they still play a role. When they play an outsized role in phonation, challenges can occur. Psychologically, people often revert to larger muscles when attempting new tasks or under stress. Phonating in new ways can often begin by employing extrinsic muscles in ways that destabilizes the target sound. Learning to check in with these muscles, to explore body/mind integration, and to employ techniques like massage can lead to helpful integration of these muscles into the overall coordination.
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The "Break"
As mentioned above, the interaction between a muscle-dominant vocal fold posture and ligament-dominant vocal fold posture can sometimes feel like a singular event. This transition can be one in which the strain on the vocal folds transfers directly from the thickening muscle (TA) to the vocal ligament, but, it can also be more gradual. When the dance between the stretchy (CT) and thickening (TA) muscles meets an abrupt transition such that the amount of vocal fold mass leaps from a muscle dominant posture to a ligament dominant posture, the entire mechanism (breath pressure, vocal fold mass, and acoustics) destabilizes for a moment, creating an auditory "break" in the sound. It can be accompanied by a sharp physical and emotional response. We choose to see this event as a part of the mechanism as a whole, rather than defining vocalization by it. There are many physical and acoustic approaches to helping all of the muscles learn to coordinate smoothly. By contrast, some styles like yodeling require that this event be emphasized. Psychological attention to allowing this transition to be an acceptable part of the process can often be as important.
Remember that the vocal folds are highly complex structures, and we can't feel them. Learning to track sensations that accompany the many and varied vocal fold adjustments can be a tricky business, but can also lead to some distinctly reliable information. The transition moment can occur at many points across the vocal range, sometimes by choice, and sometimes without intention. Learning to navigate this event can be an important part of voice training.
For more information on acoustic contributions to register changes, see our Acoustic Strategies page.
As mentioned above, the interaction between a muscle-dominant vocal fold posture and ligament-dominant vocal fold posture can sometimes feel like a singular event. This transition can be one in which the strain on the vocal folds transfers directly from the thickening muscle (TA) to the vocal ligament, but, it can also be more gradual. When the dance between the stretchy (CT) and thickening (TA) muscles meets an abrupt transition such that the amount of vocal fold mass leaps from a muscle dominant posture to a ligament dominant posture, the entire mechanism (breath pressure, vocal fold mass, and acoustics) destabilizes for a moment, creating an auditory "break" in the sound. It can be accompanied by a sharp physical and emotional response. We choose to see this event as a part of the mechanism as a whole, rather than defining vocalization by it. There are many physical and acoustic approaches to helping all of the muscles learn to coordinate smoothly. By contrast, some styles like yodeling require that this event be emphasized. Psychological attention to allowing this transition to be an acceptable part of the process can often be as important.
Remember that the vocal folds are highly complex structures, and we can't feel them. Learning to track sensations that accompany the many and varied vocal fold adjustments can be a tricky business, but can also lead to some distinctly reliable information. The transition moment can occur at many points across the vocal range, sometimes by choice, and sometimes without intention. Learning to navigate this event can be an important part of voice training.
For more information on acoustic contributions to register changes, see our Acoustic Strategies page.
In this video, a male singer glides from low in his range until his vocal folds "flip" onto their edges. Notice how the folds begin quite wide and loose and then lengthen and become more stiff across the glide, showing increased stretchy muscle (CT) activity. When the folds "flip", you can see more space between the folds, and a general thinning in the folds. Try watching without sound, and see if you can notice the moment when the change occurs.
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Amount of Vocal Fold Closure (Adduction)
4 out of the 5 muscle groups in the larynx are in charge of closing the vocal folds. The amount of closure that occurs is called adduction. If the folds are less adducted - more air escapes, the sound may be percieved as "breathy". The more adduction the folds have, the more upper harmonics will be present in the sound. See our Harmonics vs. Formants page for more information. |
Definitions
Adduction - When the vocal folds come together, vocal fold closure, necessary for singing Abduction - When the vocal folds pull apart, vocal fold opening, necessary for breathing Glottis - the slit-like opening in between the vocal folds where they meet together |
exercises that focus on coordinating laryngeal muscles
what you might hearThe sound is pressed, forced, tight
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what might be happening at the level of the larynxThe heavy muscle (TA muscle) may be more stiff and the vocal folds may be squeezing together excessively
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vocal exercises to tryLip trill with just air and then go into a lip trill with sound behind it. Notice the moment when air turns to sound. Is it forceful or easy?
Spoken exercise: Wwwwwait a minute Wwwelll Well Well Notice the ease of the 'w' sound Read a sentence out loud as if telling a story to a child Sighs Vocal fry |
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The sound is breathy, airy
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The muscle groups in charge of closing the vocal folds are not active enough, extra air is escaping through the glottis
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MiuMiuMiu
MiamMiamMiam Ngggggg GangGangGang Glides through a straw The back pressure of nasal consonants and straw phonation can encourage the vocal folds to come together |
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The voice breaks or cracks, a giant shift occurs when going from low notes to high notes
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The trade off between the stretching and the thickening muscle may be unbalanced, and/or the coordination of all muscles imbalanced.
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Slow slides on a lip trill, hum or through a straw
Think about the highest note in the phrase as you breathe in before singing. Early preparation and early transitioning can encourage a less sudden shift in muscle trade off. |
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High notes feel difficult, a feeling of reaching or pushing occurs when going up in the range
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The stretching thinning muscle may not be active enough. If the folds are allowed to stretch and vibrate on their edges, high notes may feel easier. Or, acoustic support may need to be increased to balance breath pressure.
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Puppy whines
Whimper Whine- I don’t wannaaaaaa Elf giggles, hoo hoo hoo Imagining a tiny easy sound 
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take aways
Singing and speaking involve muscle coordination. Just like other athletic activities, these muscles can be trained for optimal coordination and fatigue resistance.
Warm ups and exercises can be designed to target specific muscle groups.
Unlike some athletic activities, training the muscles involved in singing requires coordination rather than strength. Having a bulked up crico-arytenoid (CT) would probably not be beneficial if the neural pathways to coordinate its movement were not in place.
The muscles inside the larynx cannot be felt and cannot be directly controlled. The muscular sensations you might feel during phonation are probably in the jaw, tongue, neck and pharynx. Visit our Jaw, Tongue & Neck and Vocal Tract pages for more information.
The transition between muscle-dominant and ligament-dominant phonation is an event that can occur in many parts of the range. Vocalists can learn to control when that transition occurs.
Warm ups and exercises can be designed to target specific muscle groups.
Unlike some athletic activities, training the muscles involved in singing requires coordination rather than strength. Having a bulked up crico-arytenoid (CT) would probably not be beneficial if the neural pathways to coordinate its movement were not in place.
The muscles inside the larynx cannot be felt and cannot be directly controlled. The muscular sensations you might feel during phonation are probably in the jaw, tongue, neck and pharynx. Visit our Jaw, Tongue & Neck and Vocal Tract pages for more information.
The transition between muscle-dominant and ligament-dominant phonation is an event that can occur in many parts of the range. Vocalists can learn to control when that transition occurs.
