Air Pressure, Pitch Range, and Dynamics

A recent discussion over at the Trumpet Herald forum got me thinking a bit more about the relationship between the pitch and dynamic being played by a brass player and how the breathing functions. Many brass players and teachers talk about using “faster air” for high notes, “blow harder” for loud notes, or “hot, wet, breath” for getting a rich, dark sound. These sorts of descriptions are fairly common, although many variations exist and not everyone feels similarly about their effectiveness in playing and teaching.

It is, of course, necessary to consider that playing sensations are a pretty unreliable way of talking about what exactly is happening in the player’s physiology or in the acoustics of the instrument. What to one player might feel like “blowing harder” might seem more like “faster air.” Furthermore, what works for a brass student and one stage of his or her development may become counterproductive later. This is why it’s important to have a good teacher who can watch you play and make corrections as needed. Teasing out those corrections often will take the form of analogies such as the ones I described, but we have to fall back on trial and error.

All that said, I find the science behind playing mechanics and instrument acoustics fascinating. Regardless of how you feel like you play, there may be some insights we can glean as players and teachers into breathing by taking the time to learn more. This can be a controversial topic, as reading through the Trumpet Herald topic can show. It’s even been a topic I’ve blogged about here that inspired some heated debate in the comments. In part this is due to differences in opinion about whether knowing this can be helpful or is a waste of time. My thought here is that trying to learn more about the way things work is never a waste of time, provided you are aware of the risks of going down the wrong path for a bit and recognize that you might just need to backtrack. Better still is to learn from those who have already done the research and had something to say about it.

One group of researchers, Jonathan Kruger, James McClean, and Mark Kruger, replicated a famous informal experiment that Arnold Jacobs supposedly did measuring the air pressure of brass players on different instruments and comparing how much blowing pressure and airflow were used for pitches. Jacobs noted that as the blowing pressure increased as the player ascended in range while the airflow decreased. He also claimed that players of different instruments would use a similar intra-oral pressure for the same pitch, so that a trombonist playing a “high Bb” would be blowing with about the same amount of pressure as a trumpet player playing the “middle C” (both pitches would be Bb4). Kruger, et al, found some of this to be true, but some of it to be different.

Intra-oral compression does increase as pitch increases and airflow decreases as pitch increases in each of the four members of the brass family. Both measures are also sensi- tive to changes in loudness (dynamic). Figure 2 shows changes in airflow and internal air pressure for a trumpet performer ascending the open pitches from the G below middle C upward while playing as close as possible to 85 decibels. As Jacobs observed, the larger bore instruments require less intra-oral compression and produce more air- flow when playing in their normal ranges than the higher instruments. Contrary to Jacob’s assertion about the simi- larity of instruments playing the same pitch, we observed measurable differences.

Other researchers have done similar experiments and found similar results. Kenneth Berger’s article in the Journal of Applied Physiology, Respiratory and articulatory factors in wind instrument performance (full article behind a paywall, abstract only), notes that the trumpet requires more intraoral pressure that other wind instruments studied.

A third paper published by 10éme Congres Fancaise d’Acoustique is thankfully written in English here. Freour, Causse, and Cosette noted similar results. In their article, Simultaneous Measurement of Pressure, Flow and Sound during Trumpet Playing, they wrote, “…it appears that pressure increases with both pitch and loudness, that flow increases with pitch and tends to decrease with dynamic.” They also note that the results of their study open up new questions that can now be addressed, such as the influence of air compressibility and even blood distribution in the respiratory system while playing.

So what are the implications for teaching and practicing brass instruments? At the very least I think we understand that blowing pressure and air volume do depend on the pitch range and dynamic being played. Knowing this, we might want to practice and teach being more aware of how we’re blowing while playing and changing those factors. Through this awareness we can learn our personal playing sensations in such a way as to memorize the feeling of when things are sounding and feeling good as well as better troubleshoot for those times when they are not.

Darryl Jones

I think you intend to express the term air “flow” not air “volume”. These are different things but they are related. What we sense is air flow not air volume. Air Volume depends on the flow AND the length of the note or phrase.
The only air quality that the player controls directly is air pressure. The resulting air flow will depend on the acoustics of the instrument, the efficiency of the player and other factors.
A common problem in these discussions is that the subject is confined to air qualities as if they are the causative factor of pitch.
A more accurate description is that embouchure disposition determines the pitch played and the air pressure will determine the loudness of tone.

Dave

Hi, Darryl.

Yes, in the very last paragraph I meant to write “flow,” not volume. Pedantry aside, I think the point of the researchers I discussed was made.

Dave

Sven Larsson

I have wondered about Arnold Jacobs writing about the air wolume being the for the same tone for different bore intruments for years. Not so much if its true since I have been involved in an invastigation abot that, he is dead wrong, but how come he wrote that?

Elgin

“In their article, Simultaneous Measurement of Pressure, Flow and Sound during Trumpet Playing, they wrote, “…it appears that pressure increases with both pitch and loudness, that flow increases with pitch and tends to decrease with dynamic.””
Possible mistranslation? “flow increases with pitch and tends to decrease with dynamic.”

Dr. Jonathan H. Kruger

My colleagues and I answered many of these questions in our article. What surprised me however, was the lack of inquisitiveness about what actually does energize the harmonic series on a brass instrument. This blog suffers from many of the same issues that have plagued brass pedagogy from time immemorial. Airflow, Air volume – these are resultants of energy placed forth to achieve a task. Ask yourself, first, what is the task? Is it a higher note in the harmonic series, or more sound power level?

Dave

Thanks for stopping by and leaving us your comments, Dr. Kruger.

My colleagues and I answered many of these questions in our article.

Were there specific questions here that you’re referring to?

What surprised me however, was the lack of inquisitiveness about what actually does energize the harmonic series on a brass instrument.

Are you referring to the vibrating embouchure here? This specific post was just to touch on aspects of breathing that are often discussed, but seem to frequently be misunderstood among brass musicians.

This blog suffers from many of the same issues that have plagued brass pedagogy from time immemorial.

Depending on what issues you’re referring to, I feel that’s a bit of an unfair categorization. Maybe I didn’t get my point across so well here, but I’m advocating for brass players and teachers gaining a more complete understanding of the physics and mechanics behind playing a brass instrument, rather than the more traditional “imagine the sound and let the body work itself out.”

Airflow, Air volume – these are resultants of energy placed forth to achieve a task. Ask yourself, first, what is the task? Is it a higher note in the harmonic series, or more sound power level?

One of the difficulties us physics laymen/musical professionals have in discussing these things with acousticians is that we tend to use different terms, or sometimes even the same terms to mean something different. Where you are asking if the goal is a “higher note in the harmonic series,” I would think of as “tessitura.” “More sound power level” to me would be “louder dynamic.”

At any rate, I hope you will come back and answer your rhetorical questions and maybe clarify your point a bit more. I think that both myself and many of my readers could benefit a great deal from your understanding and picking your brain a bit about this topic.

Best,

Dave

Dr. Jonathan H. Kruger

If my last missive was interpreted as being too harsh than please accept my sincere apologies. It was not meant to be. It was, however, intended to be provocative. In the discussion, Sven Larsson ponders why Jacobs made that error. I and my colleagues somewhat obliquely answered that in the end notes of the article. My verbiage regarding Arnold Jacobs legacy was very carefully worded in that article. Bear in mind that I studied with the trumpet players in the Chicago symphony in the late 70’s before doing my graduate work at Eastman in the early 80’s. 3 of the 4 members of the current Chicago Symphony are former classmates of mine. Because Arnold Jacobs is so revered (rightfully so) it is very difficult to say something that may contradict him. But in fact, his legacy has unwittingly unraveled what he actually sought to do – utilize objective methodology to answer the conundrum of brass playing, rather than as you put it “the more traditional “imagine the sound and let the body work itself out.”

Again, I’m going to put this question to you. What energizes the harmonic of a brass instrument? The contributors to this discussion are getting caught in the same whirlpool of confusion regarding terminology of airflow, vs. air volume, etc. I understand that confusion, I’ve been sucked into that vortex as well. Bear in mind, however, that all of those aforementioned terms are resultants, not causes. If I drive my car down the road I sense that it is vibrating. Does that mean that the vibration causes the car to go down the road? The latter may seem like a poor analogy, but it strikes to the heart of where most brass pedagogy falls short. In other words, because I play in a symphony orchestra, and this is what I perceive when I play, therefore it must be true.

As to your last posit,

“Where you are asking if the goal is a “higher note in the harmonic series, “I would think of as “tessitura.” “More sound power level” to me would be “louder dynamic.”

The term “tessitura” is used within musical discussions to symbolize a specific sound print associated with the extreme upper register of any given instrument or voice. Thus, it is a term that is more often used in musical discussions rather than those related to a more scientific explanation. Also, please consider, that a higher note in a harmonic series is not necessarily associated with a specific pitch. When I “hit” the fifth partial on my c trumpet it is a different pitch than the fifth partial on my eb trumpet. Your last sentence regarding sound power level is more spot on, but again, the term louder dynamic is more of a musical description rather than an objective measurement such as dB. Hey, I guess you’re just a musical guy!

In the article we make the statement that airflow, air volume, air compression, air, air, air!, is more directly related to sound power level than pitch. That should really make you think.

All the best, Jonathan

Dave

Thanks again for leaving your thoughts, Dr. Kruger.

In the discussion, Sven Larsson ponders why Jacobs made that error. I and my colleagues somewhat obliquely answered that in the end notes of the article.

Keep in mind that I only linked to a symposium PDF of your study in the post above, not your actual article. In doing a search for the article itself, I came across this:

MORE AIR, LESS AIR, WHAT IS AIR

And holy cow, this is the first time I’ve seen a published paper site my dissertation! When I have time I will give your paper a thorough reading, which perhaps will help me address your Socratic questions and comments better.

Dave

Dr. Jonathan H. Kruger

Dave, yes, everything is clearer now. Yes, I have already researched your work. Had I known that you actually had not read my entire article, I would have framed my responses differently. Or… perhaps not. I look forward to your contributions after you have had an opportunity to read the article in its entirety.

Jonathan

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