Demystifying resonance and pushing

A previous article in this series, called mythbusting vocal strain, argued that the term 'strain' conflates two separate phenomena:

1. Strain as elastic deformation due to stress, something that happens to the vocal folds and is prone to causing microscopic tearing and subsequent vocal injury.

2. Strain in the sense of pushing for high notes, ie. the felt need to rely on excessive effort to ascend in pitch.

Today, we will address strain in the second sense, ie. pushing, and see how we can use resonance to avoid it.

Central to resonance is a phenomenon known as constructive interference. This happens when two waves line up so that their combination is stronger. Consider for example a playground swing: the initial push puts momentum into the swing, causing it to move. Since it moves in an arc, the movement becomes increasingly vertical as it departs from the resting position, which causes gravity to increasingly slow it down. Eventually, gravity reverses the direction of movement, but by this point the swing has reached its maximum height, so it will pick up momentum during the descent. Thus, the swing does not simply return to its resting position, but instead overshoots, causing it to move like a pendulum. If there were no friction, this movement would simply continue on forever

A swing however is heavy, especially if someone is sitting in it. Therefore, it needs a lot of momentum, and the initial push is not likely to suffice. If you want it to move in a large arc, you will need multiple pushes in succession, but if you push while the swing is coming towards you, you are decreasing its momentum and making the arc smaller. Yet by pushing while the swing is moving away from you, even if it is just beginning its descent and still moving slowly, you can add more momentum and get a wider arc.

This is known as constructive interference. The pushing can be thought of as a kind of wave that interferes with the movement of the swing — which we can also think of as a wave. For this to work, however, the waves need to match in frequency, thus maintaining the same timing — also known as phase relationship. The initial phase relationship need not produce constructive interference — the person doing the pushing can push even when the swing is coming towards him, so long as the timing matches that of the swing, but in this case, the swing will first come to a complete standstill before the pushing starts actually working.

In singing, both the vocal folds and the vocal tract act like the swing, but to make the topic easier to understand, we will consider them one at a time.

The linear source-filter model

The vocal folds act primarily to modulate airflow. Working together, they constitute a valve that periodically opens and closes. As they open, the increase in airflow causes a buildup of pressure above the vocal folds, which then propagates through the vocal tract. As they close, the airflow above the vocal folds continues, but the airflow through the glottis ceases, causing a vacuum. This vacuum pulls on air particles further along the vocal tract, rarefying them and thus propagating the vacuum.

As a pressure pulse reaches either end of the vocal tract, it is reflected. For reasons that go beyond the scope of this blog post, but which are explained here, the waves are reflected differently at the open end (ie. the mouth) than at the closed end (ie. the larynx). Specifically, high pressure turns into low pressure and vice versa at the open end, which means a pressure pulse must traverse the vocal tract four times (twice back and forth) in order to return to its initial state.

By singing at the resonant frequency of the vocal tract, we are effectively timing the movements of the vocal folds to match the reflected waves, much like with the swing, where we time our pushes to when the swing is moving away. This allows acoustic energy to build up in the vocal tract — gradually, though it is fast enough to seem instant to human ears — much like the swing gradually goes higher and higher as we push it.

To accomplish this when singing a predefined melody, we must constantly adjust the shape of the vocal tract. Since the vocal tract is not a uniform tube, we can adjust separate resonant frequencies independently by changing its shape. For example, we can move the tongue, tilt the head, narrow the pharynx, change the shape of the lips, etc. All of these allow us to modify the resonant frequencies of the vocal tract independently, which is what makes it possible for us to enunciate vowels. This, incidentally, is also why vowel modifications are so important in singing.

Nonlinear source-filter interaction

In singing, things are rarely as simple as they appear at first glance. Therefore, we must consider not only how the movements of the vocal folds excite the resonances of the vocal tract, but also how the sound in the vocal tract excites the resonances of the vocal folds. Fortunately, since the vocal folds generally vibrate in a regular (ie. periodic) manner, their resonances are not manipulated individually and we may speak of a single overall pitch with overtones following a standard harmonic series.

In understanding how reflected waves impact the movement of the vocal folds, a key term is phase relationships, which was covered briefly in the case of pushing a swing. Very briefly, we may say that when two waves have their peaks aligned so as to produce constructive interference, the waves are in phase. Conversely, when they are misaligned so that the peak of one wave corresponds to a trough of the other, we may describe them as being out of phase. If the waves are maximally misaligned, we may say that they are 180 degrees out of phase.

Airflow through the glottis is constrained by the movement of the vocal folds; the air can only escape when the vocal folds are apart and the glottis is open. In the case of the incident wave entering the vocal tract from the glottis, acoustic theory shows that the pressure is in phase with the flow. What this means is that the pressure approximately follows the glottal area — if we set aside reflected sound and focus only on the incident wave, that is.

Ideally, we want the reflected pressure from a previous pulse to arrive while the vocal folds are moving apart, and for reflected vacuums to arrive while the vocal folds are coming together. This means we want the reflected sound to arrive a bit early, which means we want to sing a bit below the resonances, or from a more practical perspective, to tune the resonances slightly higher than the sung pitch. In terms of the singer's sensation, this will be experienced as being "on top of the note" as opposed to "reaching for the note" or "pushing".

Pitch ceilings, voice cracks, and pushing

Having reached the practical section of the blog post, it seems fitting to begin with a practical demonstration. Here is a video in which YouTube creator Physics Girl tries to sing sirens through a PVC pipe, and finds that discontinuities — or voice cracks — inevitably appear around its resonant frequencies.

The pattern seen here will probably seem familiar to many beginning singers, especially those who struggle a lot with close vowels like EE (IPA: /i/) and OO (IPA: /u/). There will be these strange pitch ceilings that you run into; it will seem impossible to go higher without a voice crack, and as you go closer to the ceiling you will find yourself having to push more and more.

As Professor Joe Wolfe indicates in the video, these pitch ceilings actually correspond to the resonances of the vocal tract. Because the phase relationships between the vocal folds and the reflected sound differ above versus below resonance, we cannot sing exactly on the resonance. Also, since the phase relationships when singing above resonance are more conducive to falsetto than to modal, we are liable to experience voice cracks when trying to sing through a resonance.

As mentioned earlier, we can modify the resonances of the vocal tract independently, which is not possible with a PVC pipe. Relying on this, we are able to sing through one resonance by compensating using another resonance, which is why we do not necessarily experience a voice crack when singing through a resonance.

Alternatively, we may of course wish to stay in the lower acoustic register, but take it higher in pitch. Perhaps we enjoy the rich open sound that results from keeping the second harmonic just below the first resonance of the vocal tract (ie. yell-timbre or F1/H2 tuning, or perhaps we are singing a dramatic climax and desire a volume that is hard to achieve with a weaker resonance tuning. In such a case, we need to find ways of elevating the resonance as we go up in pitch which typically involves some combination of opening the mouth, raising the larynx, adding twang, moving the tongue, and modifying the vowels.

Seeking to avoid a voice crack, and either wanting to stay in a lower acoustic register or simply not knowing how to transition to a higher one, some singers will try to simply push closer to a pitch ceiling (from a vocal tract resonance), using an increased amount of medial compression and support power. However, in many circumstances, pushing in this manner does not enable singers to simply ignore the pitch ceiling, only to inch slightly closer to it. Even in this approach, it is still necessary to raise the larynx, open the mouth, etc., which is likely the reason why these adjustments have often been associated with pushing and improper technique. Such a singer would be well advised to simply make these modifications before starting to push, instead of making them only after having pushed as close to the pitch ceiling as possible. This has sometimes been described as "singing on the resonance" or "singing on the harmonics", and it is what provides the aforementioned sensation of "being on top of the note".

Good mixed voice and bad mixed voice

Since mixed voice typically features thinner vocal folds and weaker resonance tunings than chest voice, singers will often make up for the loss of intensity by increasing medial compression (ie. squeezing the vocal folds together). This adjustment is also often a necessary component of formant/harmonic crossings (ie. of singing through a resonance), and is even a necessary component of certain mixed voice coordinations that would otherwise go to falsetto.

This limited amount of squeezing is generally harmless, though marginally less efficient than coordinations that rely less on it. It however also has the interesting side effect of decreasing the overall amount of nonlinear source-filter interaction, and since it typically goes along with less narrowing of the epiglottic funnel, the vocal tract resonances are also weaker to begin with.

Some singers wind up using these properties of medial compression to construct a mixed voice that minimises the effect of vocal tract resonances. Since chest voice is more dependent on resonance tuning, these singers will tend to avoid it even when singing loudly, preferring to further increase medial compression instead of relying on the thyroarytenoid muscles to make the vocal folds thicker.

Conversely, a more efficient mixed voice singer will still rely heavily on resonance tunings in mixed voice, and when going from chest voice to mixed voice, instead of wholesale replacing thyroarytenoid activity with medial compression, they will simply decrease the thyroarytenoid activity. In particular, they will not stretch the vocal folds more than is required to produce the combination of pitch and intensity they are looking for.

Though the other approach requires more support power and thus makes loud volumes a lot more tiring, this is still relatively benign. However, we are at this point getting very close to a very troublesome phenomenon: squeezing spirals.

Squeezing spirals and vocal deterioration

Going high in pitch, mixed voice will naturally become belty and dramatic, making it more advisable to transition to falsetto if a mellow sound is desired. Singers who have not learned to make this transition seamlessly, and do not wish to have a voice crack may however simply try to make their mixed voice sound more "heady"by making it even thinner, less twanged, and consequently, more compressed.

Conversely, going low in pitch, mixed voice is liable to become weak and tonally inadequate. This is where it is necessary to switch to chest voice, but singers who are either timid or habituated to relying on medial compression for volume will tend to avoid this switch. In order to achieve a fuller sound, they instead lower the larynx, maintaining the pharyngeal narrowing often characteristic of mixed voice, and simply add a lot more medial compression. This way, they construct a "fake chest voice" that requires them to stretch their vocal folds even further when they go back up in pitch.

A singer singing in this way will notice considerable deterioration in their clarity of tone, dynamic range, etc., throughout a session of voice usage, which they will erroneously attribute to vocal overuse since it seems to subside with rest. If the technique is not adjusted, however, they will become just as squeezed and thin-sounding the next time they sing, and it will likely take less time on each subsequent occasion.

Thus a lengthy deterioration begins, often spanning several years, with the singer sounding increasingly introverted, the vocal folds becoming increasingly stretched and thin, and an increasing amount of support power being required to overcome the ever-increasing medial compression. This marked deterioration will typically make the singer speculate about vocal damage and make an appointment with an ENT. The subsequent laryngoscopy will show atrophied thyroarytenoids, sometimes to the extent of having bowed vocal folds and a total inability to achieve complete closure of the glottis.

I am not suggesting that all cases of laryngeal wasting are attributable to squeezing spirals — there is of course also such a thing as genuine vocal fold paresis — but it is telling that such diagnoses, including that of vocal fold paresis, seem to be much more frequent in schools of singing that demonise the use of chest voice and advocate the use of mixed voice for absolutely everything.

While squeezing spirals may seem scary, they do not have to be. They can be largely prevented by making sure to work on a strong, "unmixed" chest voice once in a while and making sure you return to a relaxed chest voice once in a while when singing, especially when going low in pitch. If you find yourself caught in a squeezing spiral you cannot break out of, being stuck in mixed voice, you need not panic; simply go low in pitch, working on open vowels for a while with a bit of twang, a low-ish larynx, confident onsets, and a relaxed inflection. Once you have found your chest voice again, try taking it up in pitch, at least to the upper half of the third octave or so.

Summary

• The vocal tract has resonant frequencies which can be adjusted individually by moving the tongue, lips, etc., which is how vowels are formed.

• When singing, especially in chest voice, we tune vocal tract resonances to match the frequency of the sound produced in the larynx (or those of its harmonics)

• Acoustic energy from the vocal tract feeds back into the vocal folds and either sustains or dampens their oscillation. To sustain it, we typically need the vocal tract resonance to be slightly higher than the note or overtone we are tuning it to.

• The sensation of "being on top of the note", as opposed to "reaching for the note", is caused by good resonance tuning.

• Pitch limits and voice cracks are generally caused by getting stuck in a particular resonance tuning and being unable to take it higher.

• These effects are less pronounced in mixed voice, especially if there is a lot of medial compression, very little epiglottic constriction, and very little thyroarytenoid activity.

• Relying on mixed voice for everything, especially low notes with loud volumes or high notes with low volumes, will tend to cause a "squeezing spiral", ie. a gradual increase in pressing and a gradual decrease in the fullness and clarity of the tone.

• Squeezing spirals are easily avoided or reversed by working on chest voice in the lower range, and by returning to chest voice when a song goes low in pitch.

Demystifying breath support

Breath support is one of the first concepts aspiring singers encounter when reading or hearing about vocal technique. Unfortunately, it is mired in myth, ill-defined concepts, and muddled thinking. Accordingly, the purpose of this post is to provide a clearer way of thinking about breath support.

To begin, we will consider the power-source-filter model of singing, which was gradually developed by various vocal scientists but which is, in the world of singing pedagogy, primarily associated with Estill Voice Training. The power-source-filter model consists of the following three parts:

• The respiratory system, which acts as the power generator

• The vocal folds, which act as the sound source

• The vocal tract, which acts as the filter

These three parts work together to produce the final sound. The lungs are compressed by the relaxation of inspiratory muscles (eg. the diaphragm) and the activation of accessory expiratory muscles (predominantly abdominal muscles). In conjunction with the vocal folds acting as a valve, this generates pressure that drives the vibration of the vocal folds. Finally, the sound is given shape by the filter as certain frequency areas are dampened and others conserved. There is a substantial interplay between the filter and sound source, but as our present focus is on the power subsystem, we will set aside the discussion of such interactions and return to them in future posts.

The first realization key to understanding support is that the lungs are, in effect, a valved container that can be pressurized, and as with any such container, the pressure can only go as high as the valve will contain. Beyond that, the valve is burst open. Moreover, a certain amount of pressure is needed simply to set the vocal folds in motion, and beneath that, no phonation will occur. Thus the vocal fold closure — ie. the tightness of the valve — narrowly constrains the amount of pressure or support energy.

What this means in practical terms is that the respiratory system and the vocal folds always work in unison. They can of course work badly in unison, but they do not work independently: a substantial adjustment in one subsystem necessarily coincides with a substantial adjustment in the other — at least if the vocal folds remain in vibration. For this reason, a dichotomy arises when singing: we can either make changes in the support and let the larynx adjust to it, or we can make changes in the larynx and let the support adjust to it. These each have their uses, which will be explored later. For now, we will simply refer to them as "breath leads tone" and "tone leads breath" respectively.

Defining support power

The second key realization is that while support can increase or decrease in intensity, the relationship between pressure and airflow is determined by the larynx (in conjunction with the vocal tract, for reasons that will be explored in future posts) and not the respiratory system. In a technical formulation, we might say that the power subsystem has a strictly one-dimensional output, ie. support power can increase or decrease, but the respiratory system cannot by itself control the degree to which that manifests as increased pressure versus increased airflow.

Let us briefly stop to consider some terminology. We have so far been referring to a power generator, and to increases and decreases in support power. Power is of course a term used in physics, measured by the unit watt. It happens to be the case that the units for airflow and pressure combine to watt. In fact, support power — also known as pulmonary power — may be technically defined as the product of lung pressure and airflow. This product is what we are referring to when speaking of the power generator and support power.

So breath support allows us to increase or decrease support power and that is all. It is in a sense charmingly simple and straightforward: just one variable, and it happens to be tightly constrained by the other two subsystems. I am afraid those who have been sold on breath support as some kind of vocal panacea have been deceived. Furthermore, it is largely the expiratory muscles that are responsible for support. Whenever you find yourself working intensely in the core musculature, using great levels of support, you are generating high levels of pressure. The idea that strong support consists of using inspiratory muscles to reduce pressure is simply incorrect, as it is the vocal folds themselves and not the inspiratory muscles that hold back the air.

Remembering our dichotomy, the "tone leads breath" approach promptly recommends itself: there are many adjustments we can make in the larynx; its output is far from one-dimensional. There is no way of qualitatively differentiating these in the respiratory system; therefore, we can get a more delicate control using "tone leads breath" than using "breath leads tone".

While this is generally true, and I do recommend this as the general strategy for singing, the opposite approach has certain situational uses which should not be neglected. In particular, there is a tendency for the false vocal folds — responsible for some types of distortion — to approximate when very great pulmonary power is employed. This mechanism is known as the Valsalva manoeuvre and it is useful in rock singing for obvious reasons. However, since approximation of the false folds when done to a lesser extent, or in combination with a different vocal tract shape, can add firmness to the tone without engaging distortion, it also has uses in styles that do not call for effects. Finally, it has some uses in stabilizing the laryngeal mechanism and preventing voice cracks, especially in the upper range.

The proper study of support

If support is one-dimensional and tends to simply adjust to the changes in the larynx and vocal tract, it may seem like there is no purpose in paying attention to it at all. This is not quite the case, as we are about to see.

Support is essentially about respiration, so it relates to a dynamic view of posture as opposed to the static view more frequently encountered. Since the ribcage is connected to the thoracic spine, which in turn is connected to the cervical spine that supports the neck and head, the postural movements we undergo when breathing will lead to changes in the vocal tract throughout a phrase. This can have profound effects on registration, but since this is something of an advanced topic, and since experienced singers typically navigate these changes fluently without ever having paid conscious attention to the subject, we shall not explore this aspect of vocal technique in this post.

The second and more important aspect of support is somatopsychic, that is, it relates to the effects of bodily movements on the mental state of the singer. The respiratory cycle becomes exaggerated in singing — the inspiration is sped up, the expiration is sustained and typically altered in intensity in either direction, etc. — and this tends to imbue the respiratory cycle with a certain style. It may be bouncy, punchy, flowing, dramatic, explosive, etc. One singer may have a relaxed posture with a slight slouch, low relaxed breathing that is mostly tidal, etc. By contrast, another singer may be doing thoracic breathing in a posture so upright and with breaths so full that the sternum elevates and creates the appearance of pride or even heroism.

The point is not that the former kind of singer is lazy and should adopt the manner of breathing used by the latter. The point is rather that these singers are likely to be singing very different songs that express different emotional states. Emotional states are however embodied in a person's posture as readily as they might be contained in a song, and just as it would be difficult to sing a mellow ballad while headbanging, so too is it hard to sing a pop song while breathing like an opera singer or vice versa.

My recommendation is this: when singing a dramatic song, use dramatic breathing. When singing a bouncy song, use bouncy breathing. When singing a relaxed song, use relaxed breathing. Always your mind should be of one intent — unless you are trying to depict a character caught up in a tense struggle against himself or some such.

It has been my experience so far that most support-related problems consist of a conflict between the musical intent and the affect embodied in the singer's movements. For example, a singer trying to sing a high note in a bold and open manner may fail because of a timidity that leads him to draw backwards and drop his gaze. In such a case, it is likely he can be helped by practising a more suitable movement without singing, then reintroducing the phrase in an easier key, and taking care to keep the movement extraverted as he approaches the original key.

Singing is essentially a particular type of acting, and nowhere does this come through more than in the study of support technique.

Summary

• The respiratory system and the larynx always work in unison and cannot diverge very far without causing the vocal folds to cease vibrating.

• Support power can increase or decrease, but cannot be qualitatively differentiated except via the larynx and vocal tract.

• Breath support is no panacea.

• Intense exertion in the core musculature — ie. "strong support" — means you are generating high pressure.

• For most singing purposes, support should "passively" adjust to changes in the larynx.

• Active support adjustments are useful for distortion effects, for a certain firmness of timbre, and for stabilizing and/or intensifying the upper range.

• Postural movements associated with respiration can affect the vocal tract shape throughout a phrase.

• When singing relaxed songs, use relaxed breathing, whereas when singing dramatic songs, use dramatic breathing, etc.

Mythbusting vocal strain

Many beginners are understandably concerned about vocal strain, especially if they notice a sudden deterioration in their singing ability following attempts to sing high notes or distortion or some similarly challenging vocal task. However, there are a lot of misconceptions about vocal strain, and these have the overall effect of associating singing with fear and, ironically, increase the amount of straining going on.

In order to know what we are talking about, it is helpful to first construct a working definition of strain. Unfortunately, the word "strain" is itself a complicated matter because it conflates at least two different phenomena, whose definitions are given here:

1. Strain as elastic deformation due to stress, something that happens to the vocal folds and is prone to causing microscopic tearing and subsequent vocal injury.

2. Strain in the sense of straining for high notes, ie. the felt need to rely on excessive effort to ascend in pitch.

To disambiguate them, we shall refer to only the former as 'strain' and the latter as 'pushing'. These two phenomena are obviously related, but they are not the same. For example, the first thing to understand about strain is that all voice usage comes with some amount of strain. The degree to which this will cause long-term vocal damage depends however on a variety of factors such as the duration and severity of strain as well as how quickly you recover. What is fine to do for a person who eats heartily, exercises, and gets plenty of rest may not be fine for someone who is eating at a caloric deficit, sleep deprived, and dealing with a concurrent illness. This means that there is no one-size-fits-all answer regarding what is safe to do with your voice and what is not.

We can however establish certain trends. For example, a physics equation from Ingo Titze's Principles of Voice Production explains that strain is proportional to pitch and amplitude. This fact may go a long way in explaining why so many clients of laryngologists are operatic sopranos, but it has also led to a tendency among some speech-language pathologists to caution people to avoid loud volumes, especially at high pitches.

In practice, this tends to cause patients to simply "curb" their voices more, ie. restrain the sound not by decreasing the intensity of the vibrations in the larynx, but merely by making the transfer of energy less efficient. The biomechanical and acoustical aspects of how this is done are beyond the scope of this post, but they will be addressed in future blog posts. For now, it is sufficient to observe that it is possible to reduce the volume without actually decreasing the pressure acting on the vocal folds or the amplitude of their vibration.

Understanding strain

To properly understand the causes of straining and their remedies, it is helpful to dig a little deeper into the working definition given earlier. Firstly, elastic deformation simply refers to a temporary change in the shape of an elastic material, like when stretching a rubber band. Stretching your vocal folds — as in mixed voice — is an example of strain in this sense, as is the wavy movement your vocal folds make when vibrating. Fortunately, vocal folds are quite elastic and are very capable of withstanding this type of strain. Had this not been the case, singing would not be possible.

Far greater strain can however result from chaotic movements in which microscopic spots on your vocal folds are displaced relative to neighbouring spots, causing microscopic strain that can far exceed that caused by ordinary singing. It is this type of strain that is prone to causing tearing and inflammation that can eventually build up to a persistent issue.

There are two main causes of such chaotic shearing forces: pressed phonation and breathy phonation. Pressed phonation involves squeezing the vocal folds together, which increases the friction between them, whereas breathy phonation involves an excess of air between the vocal folds that becomes turbulent.

Does this mean that all breathy singing should be avoided? No. While breathy singing does tend to involve higher airflow than clear singing, it is not necessarily the case that the turbulence heard as breathiness arises inside the larynx in all cases of breathy singing. Airflow can theoretically become turbulent as it passes through the vocal tract, though the extent to which this happens is not clear. However, even supposing that all breathy singing involves turbulent airflow in the larynx, this does not mean it needs to be avoided. A normal healthy individual can withstand some amount of vocal strain provided they get enough rest to recover. As a general rule, if it feels fine, and there are no apparent signs of deterioration, it is probably fine.

If there is one lesson I wish to impart about breathy phonation, it is this: breathiness is turbulent airflow, and at loud volumes, this turbulence becomes a violent turbulence, like a tiny storm inside your throat. It is for this reason that Complete Vocal Technique cautions against breathiness specifically at loud volumes. Shouting, for example, which is known in CVT as Overdrive, should be bold and clear rather than breathy.

Pressed phonation is not as much of a culprit as breathy phonation, but here too a greater intensity will tend to mean more strain. However, since pressed phonation is often associated with reductions in volume, you cannot use volume as a guide for estimating the strain caused by pressed phonation. Instead, it is to a large extent the degree of pressing that determines the amount of strain. In case your ears are not trained to easily identify the amount of strain, you can loosely estimate it by comparing the volume of a sound to the amount of effort ("support") required to produce it. For example, if you are expending a lot of effort to produce a sound of modest loudness, it is probably — but not certain to be — because of pressing.

So far however I have not found pressed phonation to be a major culprit when helping students with vocal health problems, and in fact pressing can be a useful tool to provide some safety margin against falling into the opposing pattern of excessive airflow. Manuel Garcia, the inventor of laryngoscopy, himself advocated the Valsalva manoeuvre — an extreme type of pressing — as a useful last resort for addressing excessive breathiness.

A culture of fear

Many voice teachers put a very great emphasis on vocal health and inspire fear in their students with horror stories of various vocal injuries and subsequent botched surgeries. From a commercial point of view, this serves two important functions. For one thing, it makes the students averse to experimenting on their own and thus sustains their dependence on the teacher. Secondly, it provides a handy excuse in case the student wants to learn a technique that the teacher is not capable of performing and does not know how to teach: simply call it unhealthy and urge the student to stay away from it.

This can easily become part of a whole array of control tactics such as coming up with intangible standards of correct technique that are unintelligible to the student, or alternating between subtly contradictory instructions belonging to different vocal techniques. For example, teachers may alternate between instructing students to breathe low into the back and instructing them to maintain an upright posture. These instructions are incompatible because breathing in the back requires some degree of slouching. Thus, as soon as students do the one correctly, the teacher can simply pivot to the other instruction and keep the student running in circles.

I am not suggesting that such voice teachers are conscious of using these tactics in their practice, but manipulative behaviours have a tendency to disguise themselves as sincere concern even to the person engaged in them.

Worse still, instilling fear of vocal damage can lead to a timidity that hinders the singer's sense of freedom and ease. The singer may for example hold back the volume out of a belief that loud singing is inherently unhealthy, and by far the easiest way to reduce the volume is simply to make the whole vocal mechanism less acoustically efficient by messing up the coordination in various ways. Obviously, this does not reduce straining, nor does it constitute a path to effortless singing.

The hazards of shouting

There is a widespread misconception that singing loudly, using wide vowels, or taking chest voice high in pitch will inevitably lead to vocal damage. We have already seen one reason why this is untrue: singers differ in their recovery speeds and general health, and there is no clear line to draw between damaging and non-damaging behaviours, only quantitative assessments of differing amounts of strain. However, of all vocal myths known to me, this is perhaps the most persistent, pernicious, and unfounded, so it will serve us well to address it in detail.

Firstly, it should be understood that our vocal tracts act essentially like a horn that transfers sound from our comparatively small vocal folds to the comparatively large outside air. For this reason, the vocal tract has a narrow end near the vocal folds, and this end is made even narrower in loud singing. Likewise, loud singing tends to feature a large mouth opening so as to better transfer the sound to the outside air. While there are many valid reasons to use a smaller mouth opening — faster articulation, access to close vowels, greater facility with quieter volumes — acoustic efficiency is not among them.

Secondly, while the detractors of chest voice generally associate it with pressed phonation and a muffled timbre, this need not at all be the case. A well-coordinated chest voice will have a brassy, blaring timbre (CVT Edge) or an open, spacious timbre (CVT Overdrive), and will be capable of very loud volumes at much less effort than would be required to achieve similar volumes in other coordinations.

As for pressed phonation, it is actually needed in moderate quantities not in chest voice but in the most popular approach to mixed voice. In more technical terms, as the vocal folds stretch and thin, an increased amount of medial compression becomes needed in order to maintain the glottal closure and avoid flipping into falsetto.

When people habituated to chest voice struggle with close vowels, quiet volumes, or high pitches, the problem is not an excess of facility with chest voice — as if there could be such a thing as an excess of facility with a vocal coordination — the problem is rather a lack of facility with other coordinations, be it mixed voice or falsetto, or some other coordination. To maximise technical versatility and range of expressiveness, a singer must master both chest voice and mixed voice.

Summary

• All singing involves some strain. The key to maintaining a healthy voice is to make sure you're recovering faster than you're deteriorating. Since people differ in their recovery speeds and duration of performance, there is no one true answer to which coordinations are safe and which are not.

• Loud volumes are not inherently damaging, and trying to hold back the volume is a major reason for strain in a lot of singers.

• Breathy singing consists of turbulent air that will, at loud volumes, become a violent turbulence like a tiny storm in your throat. Therefore, avoid using a breathy tone when singing loudly.

• A voice teacher keeping you in chronic fear of vocal strain is a major red flag.

• Fear and timidity are antithetical to free, effortless singing.

• Chest voice is not inherently damaging, but like all vocal techniques, it has its own strengths and limitations. Therefore it is important to develop facility with both chest voice and mixed voice.