TONE PRODUCTION
There is a lot of opinion about how tone is produced in brass instruments. This is complicated by the fact that we can’t really know what is going on inside our mouth, throat, and elsewhere in the body when we play. Douglas Yeo has written an excellent article that speaks to this. Discussion of this topic can become heated; as in my piece on buzzing, I do not seek debate. The information here is not necessary to learn how to play. It is also NOT science – it is functional paradigm – informed (to the best of my feeble ability) by science. If you are curious, wonderful, read on; if not, so it goes . . .
The Free Dictionary tells us sound is: “vibrations transmitted through an elastic solid or a liquid or gas, with frequencies in the approximate range of 20 to 20,000 hertz, capable of being detected by human organs of hearing.” That is pretty good definition – a little anthropocentric – but one gets the idea. Encyclopædia Britannica has a lot of information on sound.
The sound we hear is transmitted in waves of compression and rarefaction through the air around us. How we hear that sound is explained well here. How we create that sound with a brass instrument another matter.
“The lips don’t vibrate.” “The lips vibrate in sympathy with the vibration in the air in the instrument.” “The air in the instrument vibrates in sympathy with the lips.” “Buzz your mouthpiece.” “NEVER buzz your mouthpiece.” “The lips touch.” “The lips never touch.” Ad Infinitum – Ad Nauseum. The old parable of the Six Blind Men and the Elephant comes to mind. There are many functional paradigms for brass playing – most folk are describing the same elephant in the room. That said, here is mine:
The Free Dictionary tells us sound is: “vibrations transmitted through an elastic solid or a liquid or gas, with frequencies in the approximate range of 20 to 20,000 hertz, capable of being detected by human organs of hearing.” That is pretty good definition – a little anthropocentric – but one gets the idea. Encyclopædia Britannica has a lot of information on sound.
The sound we hear is transmitted in waves of compression and rarefaction through the air around us. How we hear that sound is explained well here. How we create that sound with a brass instrument another matter.
“The lips don’t vibrate.” “The lips vibrate in sympathy with the vibration in the air in the instrument.” “The air in the instrument vibrates in sympathy with the lips.” “Buzz your mouthpiece.” “NEVER buzz your mouthpiece.” “The lips touch.” “The lips never touch.” Ad Infinitum – Ad Nauseum. The old parable of the Six Blind Men and the Elephant comes to mind. There are many functional paradigms for brass playing – most folk are describing the same elephant in the room. That said, here is mine:
Lips Function Much Like Vocal Cords (Folds)
There are profound similarities between singing and brass playing; but there are significant differences as well. Both systems have vibrators, resonators, and articulators. In singing the resonator does not exert control over the vibrator; in brass playing it does – but not total control – we can bend pitches – a little.
Airflow is the prime driver of vibration, but cooperation between lip vibration and resonance in the instrument is vital. In singing, the articulator is after the vibrator; in brass playing, before. Further, in brass playing, the articulator can interrupt airflow and, hence, vibration; in singing it cannot. This (the tongue) can create problems for brass players.
Many students are taught the lips are pressed together and when the air pressure exceeds the muscular tension, the lips blow open, the air pressure drops, and the muscular tension closes the lips. This paradigm leads to a tight sound and fatigue; singers face similar issues – "pressed voice." Others are taught to tighten and loosen their lips to change pitch; that can be helpful for beginners, but not in the long run. And the "press and pray" system has its limitations.
Brass tone production is analogous to phonation. A simple definition of phonation is “the process by which sound is produced.” Generally, phonation refers to speech or singing. The understanding of phonation (like all science) is evolving. The late 1950’s brought the Myoelastic Aerodynamic Theory of Phonation (or “MEAD”). This theory consists of an interaction of muscular forces, elastic recoil forces, and aerodynamic forces. It still has currency.
The Bernoulli principle and the Venturi effect are involved. The first means when air speeds up air pressure decreases; the other means when air moves through a constriction, it speeds up. (Bernoulli and Venturi also impact other areas of brass playing, like inhalation and articulation.)
A thorough discussion of Vocal Fold Physiology can be found here and Encyclopedia Britannica addresses the Theory of Voice Production here.
Roughly, MEAD postulates when airflow through the vocal folds (that are close enough together – "approximated"); the resultant Bernoulli forces create a relative vacuum that “sucks” them together; they touch, breaking the vacuum; air pressure then blows them apart and elasticity combined with “suction” brings them together again, over and over. This article*** speaks to, “The voice source, i.e., the pulsating transglottal airflow . . ." This opening and closing releases puffs of air – or compressions and rarefactions. These resonate in the vocal tract, and voila! Phonation!
Vocal tract resonance reinforces and amplifies the tone; it also emphasizes certain frequencies and damps others, this determines timbre. Interestingly, the sound of vocal fold vibration – absent resonance – is frequently described as “buzzing” and compared to buzzing a trumpet mouthpiece. More on resonance later.
So, airflow initiates and drives the vibration and we hear the resultant resonance. Brass instruments function much the same way. (Most explanations start with folds closed, but phonation functions either way, and starting with lips open – but close enough to vibrate readily – works better for brass.) Airflow also contributes to frequency selection.
Faster air creates greater relative vacuum which “sucks” the folds/lips together sooner yielding a higher frequency. In Fundamentals of Musical Acoustics, Aurthur Benade tells us “the speed of the airflow only slightly influences the frequency of this oscillation; the predominant control comes from the mass of the vocal cords and the muscle tension set up in them.” Arnold Jacobs spoke of the "length, thickness, and tension of vibrating surface." However, most brass pedagogues agree airspeed and air flow are significant factors in brass playing.
The vocal folds function differently in different registers; different "mechanisms" are involved. This impacts brass tone production, too. Different instruments operate in different registers and can use different mechanisms, frequently leading to disagreement regarding tone production – see About Buzzing.
Airflow is the prime driver of vibration, but cooperation between lip vibration and resonance in the instrument is vital. In singing, the articulator is after the vibrator; in brass playing, before. Further, in brass playing, the articulator can interrupt airflow and, hence, vibration; in singing it cannot. This (the tongue) can create problems for brass players.
Many students are taught the lips are pressed together and when the air pressure exceeds the muscular tension, the lips blow open, the air pressure drops, and the muscular tension closes the lips. This paradigm leads to a tight sound and fatigue; singers face similar issues – "pressed voice." Others are taught to tighten and loosen their lips to change pitch; that can be helpful for beginners, but not in the long run. And the "press and pray" system has its limitations.
Brass tone production is analogous to phonation. A simple definition of phonation is “the process by which sound is produced.” Generally, phonation refers to speech or singing. The understanding of phonation (like all science) is evolving. The late 1950’s brought the Myoelastic Aerodynamic Theory of Phonation (or “MEAD”). This theory consists of an interaction of muscular forces, elastic recoil forces, and aerodynamic forces. It still has currency.
The Bernoulli principle and the Venturi effect are involved. The first means when air speeds up air pressure decreases; the other means when air moves through a constriction, it speeds up. (Bernoulli and Venturi also impact other areas of brass playing, like inhalation and articulation.)
A thorough discussion of Vocal Fold Physiology can be found here and Encyclopedia Britannica addresses the Theory of Voice Production here.
Roughly, MEAD postulates when airflow through the vocal folds (that are close enough together – "approximated"); the resultant Bernoulli forces create a relative vacuum that “sucks” them together; they touch, breaking the vacuum; air pressure then blows them apart and elasticity combined with “suction” brings them together again, over and over. This article*** speaks to, “The voice source, i.e., the pulsating transglottal airflow . . ." This opening and closing releases puffs of air – or compressions and rarefactions. These resonate in the vocal tract, and voila! Phonation!
Vocal tract resonance reinforces and amplifies the tone; it also emphasizes certain frequencies and damps others, this determines timbre. Interestingly, the sound of vocal fold vibration – absent resonance – is frequently described as “buzzing” and compared to buzzing a trumpet mouthpiece. More on resonance later.
So, airflow initiates and drives the vibration and we hear the resultant resonance. Brass instruments function much the same way. (Most explanations start with folds closed, but phonation functions either way, and starting with lips open – but close enough to vibrate readily – works better for brass.) Airflow also contributes to frequency selection.
Faster air creates greater relative vacuum which “sucks” the folds/lips together sooner yielding a higher frequency. In Fundamentals of Musical Acoustics, Aurthur Benade tells us “the speed of the airflow only slightly influences the frequency of this oscillation; the predominant control comes from the mass of the vocal cords and the muscle tension set up in them.” Arnold Jacobs spoke of the "length, thickness, and tension of vibrating surface." However, most brass pedagogues agree airspeed and air flow are significant factors in brass playing.
The vocal folds function differently in different registers; different "mechanisms" are involved. This impacts brass tone production, too. Different instruments operate in different registers and can use different mechanisms, frequently leading to disagreement regarding tone production – see About Buzzing.
How do we control airspeed?
With the Venturi effect. When air flows through a constriction in a tube, it speeds up. The greater the difference in diameter, the faster the air. A “nozzle” consisting of lips, tongue, teeth, and jaw (shape of the oral cavity) assists controlling airspeed. (There is no analogous mechanism in phonation.) Tongue-level and vowel analogies are common pedagogic tools tom this end. There is a tool to help optimize your "nozzle" here. Also, there are other factors that control frequency of vibration in this system. The shape of the oral cavity also affects resonance.
Sarah Willis participated in a study at the Max-Planck Institute in Göttingen using magnetic resonance imaging (MRI). This video is fascinating throughout, but this spot speaks to airspeed.
By the way, I feel the terms slow and fast are frequently used imprecisely. Many say "fast air" when they mean high flow rate. Airspeed is measured in distance over time – feet per second. Airflow is measured in volume over time – liters per minute. These are two discrete quanta and usually mutually exclusive – or at least inversely proportional – in brass playing.
This video touches on airspeed control.
Sarah Willis participated in a study at the Max-Planck Institute in Göttingen using magnetic resonance imaging (MRI). This video is fascinating throughout, but this spot speaks to airspeed.
By the way, I feel the terms slow and fast are frequently used imprecisely. Many say "fast air" when they mean high flow rate. Airspeed is measured in distance over time – feet per second. Airflow is measured in volume over time – liters per minute. These are two discrete quanta and usually mutually exclusive – or at least inversely proportional – in brass playing.
This video touches on airspeed control.
And this Facebook post, from Luke Malewicz, while discussing a specific technique, illustrates airspeed.
Other factors that control frequency (pitch)
Another analogy can be drawn between vibrating lips and vibrating strings. Longer strings vibrate slower. So do heavier, thicker strings. The lip muscles and teeth help to control the length and mass of the vibrating surface. The teeth act as the “fingerboard.” The mouthpiece rim defines the length of the "fingerboard."
For low notes, use heavier, thicker lips, copious, wider, thicker – and SLOWER air – nothing kills low notes like fast air! (Low notes don't last very long.)
The factors that contribute to frequency include:
The proximity of the lips and the size of the aperture affect the airflow (as does the shape of the oral cavity). The aperture should be a result of airflow, not a shape you make and then blow through. In phonation, the “Firmness of Vocal Fold Closure” affects intensity and quality of tone; this is true for the lips, too. Firmness of closure is affected by elasticity, viscosity, and tension.
The “aperture” is closed much of the time. The University of Minnesota Department of Otolaryngology tells us the longer closure lasts, the louder “the sound coming directly from the vocal folds” is. They go on to say, “The loudness of the sound coming out of the MOUTH is a different matter" (see "Resonance" below). They also point out the similarity between “blowing into the mouthpiece of a trumpet, and then blowing into the mouthpiece when it's connected to the rest of the trumpet,” as does the American Academy of Otolaryngology.
Professor Eric Armstrong of York University, writes “As we get louder: the [vocal] folds don't open any further than usual, but they stay closed longer, creating more distinct 'puffs of air' – a greater difference in the low and high pressure levels; the folds are pressed together more firmly; we create high, sub-glottic pressure against the folds to compensate . . .”
The Goldilocks Rule applies: lips too tight or too loose – too little air or too much – or just right! Voice scientists speak of pressed, breathy or resonant voice qualities being related to laryngeal resistance.
Lip tension is a factor too – but – a string player doesn’t adjust their tuning pegs on the fly. They tune each string to a fixed tension, change string length (and mass) with their fingers on the fingerboard, and switch between thinner and thicker strings. The brass player should keep the lips taut enough to vibrate. There is an ideal tension (Goldilocks), not unlike a drumhead. (That may be enough analogies.)
BecomeSingers.com tells us, "When your vocal cords don’t resist airflow efficiently, then all the cords will start leaking excessive air. When this happens, the resultant sound becomes dull and airy, lacking vibrancy. You see, when your vocal cords don’t use air efficiently, you will run out of too much air faster, and this will make you compensate it by pushing harder and gasping for more." It should be noted this not a matter of squeezing the lips together, but rather keeping them close together and allowing them to open and fully close – a paradox of strength and relaxation – what James Stamp may have meant by a "close vibration." (Full closure may not happen in the upper register. See About Embouchure Shifts.)
NOTE: SingWise.com warns one can “blow them [folds/lips] aside and interrupt vibration.” I "preach" there are only two "sins" in brass playing:
There is more information on the “About Buzzing” and “About Embouchure Shifts” and "Airflow Through the Instrument?" pages.
For low notes, use heavier, thicker lips, copious, wider, thicker – and SLOWER air – nothing kills low notes like fast air! (Low notes don't last very long.)
The factors that contribute to frequency include:
- The elasticity, viscosity, thickness, mass, length, and tension of the lips (the “string”);
- The volume and velocity of the airflow (the “bow”).
The proximity of the lips and the size of the aperture affect the airflow (as does the shape of the oral cavity). The aperture should be a result of airflow, not a shape you make and then blow through. In phonation, the “Firmness of Vocal Fold Closure” affects intensity and quality of tone; this is true for the lips, too. Firmness of closure is affected by elasticity, viscosity, and tension.
The “aperture” is closed much of the time. The University of Minnesota Department of Otolaryngology tells us the longer closure lasts, the louder “the sound coming directly from the vocal folds” is. They go on to say, “The loudness of the sound coming out of the MOUTH is a different matter" (see "Resonance" below). They also point out the similarity between “blowing into the mouthpiece of a trumpet, and then blowing into the mouthpiece when it's connected to the rest of the trumpet,” as does the American Academy of Otolaryngology.
Professor Eric Armstrong of York University, writes “As we get louder: the [vocal] folds don't open any further than usual, but they stay closed longer, creating more distinct 'puffs of air' – a greater difference in the low and high pressure levels; the folds are pressed together more firmly; we create high, sub-glottic pressure against the folds to compensate . . .”
The Goldilocks Rule applies: lips too tight or too loose – too little air or too much – or just right! Voice scientists speak of pressed, breathy or resonant voice qualities being related to laryngeal resistance.
Lip tension is a factor too – but – a string player doesn’t adjust their tuning pegs on the fly. They tune each string to a fixed tension, change string length (and mass) with their fingers on the fingerboard, and switch between thinner and thicker strings. The brass player should keep the lips taut enough to vibrate. There is an ideal tension (Goldilocks), not unlike a drumhead. (That may be enough analogies.)
BecomeSingers.com tells us, "When your vocal cords don’t resist airflow efficiently, then all the cords will start leaking excessive air. When this happens, the resultant sound becomes dull and airy, lacking vibrancy. You see, when your vocal cords don’t use air efficiently, you will run out of too much air faster, and this will make you compensate it by pushing harder and gasping for more." It should be noted this not a matter of squeezing the lips together, but rather keeping them close together and allowing them to open and fully close – a paradox of strength and relaxation – what James Stamp may have meant by a "close vibration." (Full closure may not happen in the upper register. See About Embouchure Shifts.)
NOTE: SingWise.com warns one can “blow them [folds/lips] aside and interrupt vibration.” I "preach" there are only two "sins" in brass playing:
- Not blowing; and
- Over-blowing!
There is more information on the “About Buzzing” and “About Embouchure Shifts” and "Airflow Through the Instrument?" pages.
Resonance
Resonance is a huge part of the equation. It is, in fact, the goal. Resonance is what the listener hears, not the lips/folds vibrating. There are differences between vocal and brass resonance The singer’s primary resonator is the vocal tract. For brass players, there is some resonance in the vocal tract, but the primary resonator is the instrument. Resonance effects tone quality in both cases, but frequency of vibration (pitch) is very strongly affected by resonance in brass instruments, not so much in singing. Pitch bending is limited (but possible) in brass and completely facile in singing.
Robert T. Sataloff wrote in Scientific American in 1992, “When the vocal folds vibrate, they produce only a buzzing sound. That sound resonates, however, throughout the supraglottic vocal tract, which includes the pharynx, the tongue, the palate, the oral cavity and the nose. That added resonance produces much of the perceived character and timbre, or vocal quality, of all sounds in speech and song.”
NOTE: For years, "head voice" and "chest voice" have been taught as though there is resonance in those anatomic regions. This thinking persists and even invades brass pedagogy here and there. William Vennard wrote, “It seems that several cavities which have been thought important as resonators, either are inadequate as such, or are subject to no control, so that it is useless to bother our heads about them. The chest is full of a spongy material which would dampen rather than resonate. The sinuses have such small openings that they cannot be considered a part of the resonance system. The trachea may cause register difficulties, but these are corrected by acquiring laryngeal skill, not by adjusting the trachea.”* The "supraglottic vocal tract" for voice and the instrument for brass are the primary resonators. The vocal tract is a factor in brass playing (it's how we make didgeridoo noises on the trombone), but it is secondary. Messrs. Campbell, Gilbert, & Myers tell us, "The influence of the player’s windway is much more effective in the didgeridoo than in most conventional brass instruments because the didgeridoo does not have a mouthpiece with a constricted throat: the lips of the player vibrate directly against the open end of the tube, typically with diameter 30–50 mm.”**
But I digress . . .
Resonance helps to sustain lip vibration, and vice versa, sort of like pushing a child in a swing sustains swinging. In brass playing, when resonance fully cooperates ("with the same frequency and in the same phase") with vibration, effort is reduced and tone is better.
When the lips begin to vibrate, at (or near) a frequency that corresponds to one of the harmonics in the instrument, the puffs of air set up a standing wave (a great analogous video demo here) – resonance! This reinforces lip vibration and will take control of the frequency of vibration. Resonance is stronger than lip vibration; it will "drag" the lips, "kicking and screaming," to the pitch the horn is tuned to. If the lips are initially vibrating at the frequency the horn is tuned to, all is well. If not, they will “fight” – tone and attack will suffer – and the lips will fatigue.
In The Singing Trumpet, Peter Bond writes, “A falsetto singing model raises the soft palate, creating a mouth shape conducive to playing in treble clef. Pitches can be ‘placed’ as if singing in the ‘head voice.’ Vocal placement can also overcome many of the classic intonation problems. This is much easier than ‘lipping’ or bending notes.” The "falsetto" shape has more to do with the trumpet than the trombone. However, research has shown tuning oral cavity resonance can assist in very high notes. Research also shows instrument resonance diminishing in the upper end of the harmonic series; there may be a correlation. Even below the staff, "a mouth shape conducive to playing" the pitch in question is vital – I think this has more to do with airflow than resonance.
As Mr. Bond points out, mouth shape adjustment is superior to "lipping" notes in tune. I don't like the term "lipping" – there's more going on than lips – and distorting the embouchure to tune can have deleterious effects. Just blow the note you want to hear. The great thing about the trombone is we can put the slide in the right place and avoid "lipping" altogether – but mouth shape still matters! (See Tuning Slide and Slide Positions.)
The mouth has a specific shape for every pitch. Vowels can be an analogous guide to these shapes. Playing bottles can illustrate tuning the oral resonance and shaping the "nozzle" – as can whistling. Even faux whistling can help if one can't whistle or the notes are out of range. Bill Watrous was a tremendous whistler, as is Malcolm McNab. I believe there is a connection. (The whistling analogy has more to do with the tongue than the lips. The whistling embouchure is much more puckered than the trombone embouchure.)
See Michael Mulcahy on Sarah´s Horn Hangouts (the whole session is great, as are all Sarah's Hangouts, but also see elephants).
I have seen this attributed to Joe Alessi: “One crucial component of a successful high register is to increase your speed of air. Try using the syllable ‘tee’ which will cause the air to spin faster over the arched tongue. It is exactly like whistling.” I'm not so sure about "tee"; but just whistle some tunes and trills, and feel what the tongue does. Mr. Bond also wrote, “Arching the tongue in the back of the mouth (as if to pronounce ‘cookie’). . . . creates resistance in the wrong place, starving the embouchure of wind . . . The forward tongue arch can help generate wind velocity for the upper register . . . (exaggerated ‘HISSSS)." I teach "shh" and "sss" for very high notes – along with various vowel approximations. In When Science Meets Brass, published in The Instrumentalist in 2017, Peter W. Iltis writes, regarding the Max-Planck Institute MRI studies, ". . . it appears that the tongue assumes a low, pulled-back position during lower notes and progressively moves forward and upward in the mouth as higher pitches are played."
Adam Rapa has an interesting take on this here, and here.
Buzzing the mouthpiece is one tool to facilitate cooperation between vibration and resonance. Breath attacks, like those in this set up drill, help to allow the lips to find the most effortless way to vibrate – when, where, and how, they “want” to vibrate – in cooperation with the resonance in the horn. Pitch bending is useful to find where that "sweet-spot" is. Of course, tuning the instrument (slide position) is important, too.
Coordination
In short, tone production is more efficient – EASIER – BETTER – when all these factors are in tune, in sync, coordinated, and cooperating – but airflow is the prime driver. Do what you will with the “string” – there will be no tone if you don’t “draw the bow” across it. (Much can be learned watching string players use the bow.
Dr. H. Lloyd Leno's film, "Lip Vibration of Trombone Embouchures" may be of interest.
A trumpet player's lip vibration can be observed here.
This video of vocal fold vibration illustrates the similarity.
Then there's Arnold Jacobs . . .
A trumpet player's lip vibration can be observed here.
This video of vocal fold vibration illustrates the similarity.
Then there's Arnold Jacobs . . .
AND . . .
These videos by Mark Van Raamsdonk are pretty good:
First, he is right, but there are more parts of this "elephant."
A couple things:
1. He's a scientist, not a player.
2. Tone can start with the lips together – or apart.
3. While the lips do enter the mouthpiece, the drawings are misleading.
4. There are more factors than lip tension in registration – mass for one.
For a deeper dive (but "the videos assume no physics or mathematics background beyond basic everyday mathematical concepts"), see:
A couple things:
1. He's a scientist, not a player.
2. Tone can start with the lips together – or apart.
3. While the lips do enter the mouthpiece, the drawings are misleading.
4. There are more factors than lip tension in registration – mass for one.
For a deeper dive (but "the videos assume no physics or mathematics background beyond basic everyday mathematical concepts"), see:
PBS's Crash Course in Physics is excellent. It is aimed at younger minds.
*Vennard, William “Singing, the Mechanism and the Technic, Revised Edition, Greatly Enlarged 1967.” Carl Fischer, Inc., 1968, pp. 96.
**Campbell, Murray; Gilbert, Joël; Myers, Arnold. The Science of Brass Instruments (Modern Acoustics and Signal Processing) (pp. 541-542). Springer International Publishing. Kindle Edition.
***Svante Granqvist, Stellan Hertegård, Hans Larsson & Johan Sundberg 2003. Simultaneous analysis of vocal fold vibration and transglottal airflow: exploring a new experimental setup, Speech, Music and Hearing, KTH, Stockholm, Sweden TMH-QPSR, KTH, Vol. 45: 35 - 46, 2003
*Vennard, William “Singing, the Mechanism and the Technic, Revised Edition, Greatly Enlarged 1967.” Carl Fischer, Inc., 1968, pp. 96.
**Campbell, Murray; Gilbert, Joël; Myers, Arnold. The Science of Brass Instruments (Modern Acoustics and Signal Processing) (pp. 541-542). Springer International Publishing. Kindle Edition.
***Svante Granqvist, Stellan Hertegård, Hans Larsson & Johan Sundberg 2003. Simultaneous analysis of vocal fold vibration and transglottal airflow: exploring a new experimental setup, Speech, Music and Hearing, KTH, Stockholm, Sweden TMH-QPSR, KTH, Vol. 45: 35 - 46, 2003