Since as long as anyone can remember brass players have been trying to figure out ways to increase their range, play louder, and get around their horns faster. A few of them occasionally even ponder about how to play more musically, get a warmer sound, refine their articulations, play in tune/in time better, and even how to listen better in ensembles. Being a professional trombonist with a background studying physics and acoustics, I am often asked very specific questions from my colleagues about how brass instruments really work. I have decided to devote this month’s blog post to a wide assortment of interesting tidbits about brass playing that I have accumulated over the years. If you have ever played, taught, conducted, sat in ensembles near, composed for, or even just listened to brass instruments, then you will want to read this. (And consequently, if you have no interest in brass instruments or brass playing whatsoever you will want to skip this month’s biog.)
Understanding how any acoustic instrument works ultimately begins with understanding its resonance response. Resonance is a word thrown around quite often in musical circles without any specific reference to what exactly it is. I have heard many musicians use the term resonance to describe a quality of sound (i.e. “this will create more resonance in your sound”), and according to most standard dictionaries this is a perfectly acceptable use of the word. However, when physicists discuss resonance they are referring to something very specific. Physical resonance refers to the phenomenon whereby one oscillating system can drive the oscillations of another. My more loyal readers might remember that I have written about this topic in the past (see Is More Resonance Always a Good Thing?).
A brass player makes a sound by buzzing their lips against their mouthpiece rim. This in turn will excite a particular resonant frequency from their instrument which will radiate out from the bell into whatever acoustic space they occupy. For any given fingering (or position) on a brass instrument, the instrument can only vibrate at certain precise frequencies (called partials). If the lips buzz precisely at one of the frequencies the instrument is capable of vibrating (i.e. tuned right in the center of one of the partials), the instrument will respond very quickly and efficiently with a very rich tone quality. In other words, it will resonate to the best of its ability. However, if the player’s lips are vibrating slightly too sharp or too flat for where the partial is tuned, then the instrument will not respond as quickly or efficiently. The sound quality will be deadened and take a great deal more effort to make. In other words, it will not resonate to the best of its ability (or in an extreme case at all).
This brings up an important point. There are two ways to think about intonation on a brass instrument: 1) how well the instrument is in tune with everyone else in an ensemble, and 2) how well the player’s buzzing lips are tune with the instrument itself. The former is what most of us typically call “intonation,” but the latter shows up in almost everything else most brass players commonly struggle with—inconsistent attacks, distorted tone quality, poor endurance, limited range, lack of flexibility, and even affects the choice of equipment we use. It all relates to how these instruments resonate. Since brass instruments have such an incredibly high quality factor (a physicist’s term for how much potential resonance they can make) compared to other acoustic instruments, they are capable of some of the most intense resonance imaginable when played well. However, this high quality factor also exacerbates how fickle sound production on brass instruments can be if not played well.
Let’s first look at attacks. A quick loud accent tends to cause many brass players to overshoot the pitch for the attack of the note. This of course ruins the resonance during the attack, resulting in a dull sounding accent. I have overheard too many directors over the years insisting to their brass section that they need to tongue harder to get a more pointed articulation. By tonguing harder, the brass players tend to overshoot the attack even more which further deadens the note. I have often had success when coaching brass players to instead encourage them to “attack right in the center of the note” to achieve the desired effect. This subtle change in language often clues players in to what specifically is ruining their attacks while simultaneously giving them a simple musical goal they can remember. I like to think of the attack of a note as the gateway to a great tone. In my experience, a lousy attack will tend to ruin the tone quality of the entire note. Likewise, a perfectly centered attack makes getting a beautiful tone on that note very effortless.
Another common complaint among many brass players is that of poor or inconsistent endurance. While many assume that better endurance on a brass instrument is primarily about building strength in the embouchure muscles, the role of resonance is perhaps an even bigger determinant. If every note, from attack to release, were perfectly centered in the middle of each partial, then the player would get a maximum amount of resonance from the instrument on that note. This means that the lips can buzz relatively quietly and still create a great deal of sound output. However, if the notes are not centered within the partial, then the resonance is significantly reduced. It will take considerably more effort to get only a small amount of sound output. When teachers emphasize the role of strength training, they are often inadvertently encouraging their students to push the buzzing pitch sharp within the partial. The student exerts more and more effort, pulls the pitch sharp, and gets less and less sound on that note due to the reduced resonance. If brass players could instead keep every note they play perfectly centered, they would likely notice a huge improvement in their endurance.
Unfortunately for all of us, the advantages of resonance wear off as we ascend in range. All else being equal, higher notes will be quieter than lower ones on any brass instrument. This is why brass players often feel the need to blow harder and harder as they ascend—to keep the same sound output despite the reduced resonance. This is where the choice of equipment can make a big difference. Certain combinations of mouthpiece, bore, and bell size can create either a brighter or darker sounding resonance. Brighter sounding equipment tends to respond more quickly, sound thinner/clearer, resonate better into the upper partials, and not project as far out beyond the bell. Darker sounding equipment tends to respond more slowly, sound wider/more diffuse, resonate less well in the upper partials, and project much further into a large acoustic space. In other words, all equipments choices are a tradeoff. A player willingly sacrifices certain attributes for other ones based on their music needs. Many players will even use multiple pieces of equipment on a regular basis to be able to function in a maximum number of musical environments. Younger and developing brass players should be encouraged to choose standard equipment that is fairly middle-of-the-road before moving onto more specialized options.
Of course no discussion about the mechanics of brass playing is complete without at least a brief mention of the controversies surrounding how in fact the embouchure works. If one were to survey just a handful of the books which have been published on the subject of brass embouchure (not to mention what one finds via an internet search these days), it would quickly be concluded that there are as many theories about embouchure as there are brass players. Rather than risk sounding like just another one of them, I will only mention a few brief points on which there seems to be broad agreement:
1) The spacing between the lips, the position of the corners of the mouth, and the amount of pressure on the lips from the mouthpiece seem to be critical factors that determine whether or not the embouchure is even able to vibrate at all. Care must be taken to make sure the lips are not too far apart or being pushed too tightly together, the corners of the mouth aren’t pulled too much into a pucker or smile, and the mouthpiece is only being pressed against the lips as much as it has to be to keep a hermetic seal.
2) There is a certain ratio of air flow to embouchure tension that produces the easiest possible vibration from the embouchure. Excess tension in one’s exhalation tends to reduce air flow. It leads to the player trying to compensate with extra tension in the embouchure in order to keep the vibration going. This never ends well. The better solution is always to find ways to eliminate excess tension from the body during exhalation so that the air can move more freely through the embouchure. Eliminating it during one’s inhalation is not a bad idea either.
3) The amount of mass of lip tissue that is positioned to be able to vibrate freely determines the frequency of vibration of the lips. In other words, the embouchure shrinks to play in the upper register and expands to play in the lower register. This vibratory mass is regulated mainly by the tension in the corners of the mouth and the degree to which the lips are rolled in or out. However, every embouchure is unique in exactly how it accomplishes this. It takes years of practice with the help of an experienced teacher to be able to learn how to navigate the entire range of a brass instrument. It is not a matter of strength but rather of precise coordination.
4) There is some controversy surrounding the role of tongue position in relation to sound production. I am of the opinion that vowel manipulation can help to facilitate certain registers. A higher tongue arch (“eee” vowel) creates a smaller oral cavity behind the vibrating embouchure that can make the high register speak more easily. A lower tongue arch (“ahhh” vowel) creates a larger oral cavity to help low notes speak. I believe that the oral cavity functions as the back-most part of the instrument itself. Brass instruments are known to physicists as “closed-pipe resonators,” and the oral cavity is the “closed” part of the instrument. Therefore, manipulating its size for different registers makes sense to me. I’ve also had very positive results doing this, and it seems to have helped many of my students. I would encourage anyone, before simply rejecting this notion, to experiment with it. In fact, I believe that many players already manipulate vowels while they play without realizing it. Some colleagues of mine who have studied X-ray images/videos of brass players discovered this to be the case as well.
So how is any of this above information useful to non-brass players? These are the types of issues that confront brass players every time we attempt to play our instruments. We are each in various stages of working them all out. Conductors should be very careful about the kind of language they use when working with especially younger or more inexperienced players. Composers should be mindful of what they ask of the brass players who are willing to play their music. No matter what instrument we choose to play, there will be hurdles to overcome. Playing a brass instrument is a very different experience than playing a woodwind, string, percussion, or keyboard instrument. After having discussed all of the challenges confronting brass players, let’s remember what we get in exchange for all of these problems: an amazing amount of acoustic resonance that is unmatched by any other instrument family. When played well, nothing else sounds anything like these wonderful instruments.
For a more physically rigorous understanding of how brass instruments work, please click here (http://newt.phys.unsw.edu.au/jw/brassacoustics.html).