A trumpeter in a laboratory study blew at about 25 kPa on the highest notes, more than the roughly 18 kPa of normal systolic blood pressure (Fletcher and Tarnopolsky, JASA 1999). That pressure drives lips that buzz against an air column whose resonance peaks sit within about one percent of the notes played: ten trombonists sounded about 1.1% above the bore’s impedance peak (Boutin et al., JASA 2015). A 2026 study measured horn players pressing the mouthpiece against their lips with an average 40 N on a high F5 (Hirano and Kinoshita, JASA 2026), and in a student orchestra the trumpeter’s average daily sound dose reached 88.4 dB(A) (Backus, Clark and Williamon, ISPS 2007). We aggregated data from the Journal of the Acoustical Society of America, Acta Acustica, the Forum Acusticum 2023, 2025 and 2026 proceedings, the Vienna Talk on Music Acoustics, the Australian Acoustical Society, and more than a dozen other papers and theses. All of this happens before the room gets involved, which is the subject of our concert hall reverberation and clarity statistics.
TL;DR
- A trumpeter used about 25 kPa blowing pressure on the highest notes, vs about 18 kPa normal systolic blood pressure (Fletcher and Tarnopolsky, JASA 1999).
- Simulated mouthpiece pressure peaks sit around 790 Hz for trumpet, 660 Hz for cornet and 1150 Hz for flugelhorn (Rose and Holloway, Acoustics 2012).
- Horn mouthpiece pressing force rose from an average 5 N on F2 to 40 N on F5 at mezzo-forte (Hirano and Kinoshita, JASA 2026).
- A sharp trumpet attack started with a mouth pressure jump of almost 2 kPa, a soft one with less than 1 kPa (Hruska et al., Vienna Talk 2015).
- Fortissimo trombone shock waves produce upper harmonics that can extend beyond 40 kHz (Campbell and Myers, Forum Acusticum 2023).
- Without a hand in the bell, horn impedance peaks fade above 450 Hz and vanish above 750 Hz (Dell et al., ISMA 2010).
- Damping a trumpet bell shifted the fundamental’s relative power by more than 3 dB (Moore et al., Acta Acustica 2005).
- Surface finish explained 0.43% of acoustic feature variance vs 5.22% for the player (Oehler et al., Forum Acusticum 2026).
- A student trumpeter’s average daily dose was 88.4 dB(A) vs 77.1 dB(A) for the double bass (Backus et al., ISPS 2007).
- Across 12 copied backbores, total volume did not strongly track timbre, but shape did (Frost, University of Washington 2014).
1. Input Impedance Peaks: How the Bore Builds a Harmonic Series
Input impedance is the ratio of the oscillating pressure to the oscillating air flow at the mouthpiece, measured one frequency at a time. Where it peaks, the air column pushes back hardest on the lips, and that feedback is what locks the lips onto a note. A plain cylinder closed at the lips only offers resonances in the odd ratio 1:3:5:7, while a trumpet-like bore offers 2:3:4:5 (UNSW Music Acoustics, Brass acoustics introduction). The whole craft of brass design is turning the first set into the second.
The bell does most of that work. Its flare reflects low frequencies early, shortening the acoustic length by different amounts at different frequencies, so the odd resonances shift into a complete harmonic series with a detuned lowest resonance, the pedal note (Moore, Acoustics Today 2016). The numbers below show how tight the alignment is and how quickly it drifts after a few seconds of playing.
| Metric | Value | Source |
|---|---|---|
| Length of a modern trumpet, most of it cylindrical tubing | About 1.4 m | Moore, Acoustics Today 2016 |
| Open-note resonances of a Bb trumpet, cornet or flugelhorn (pedal note excluded) | Approximately multiples of 116 Hz | Rose and Holloway, Acoustics 2012 |
| Second, third and fourth bore impedance peaks of a tenor trombone (all test conditions) | 113.0-113.9 Hz, 170.9-172.1 Hz and 227.7-229.4 Hz | Boutin, Fletcher, Smith and Wolfe, SMAC 2013 |
| Average fall in trombone impedance peak frequencies measured after 3 s and after 10 s of playing | 0.48% and 0.62% | Boutin, Fletcher, Smith and Wolfe, SMAC 2013 |
| Played frequencies of the trombone’s Bb2 and Bb3 in the same tests | 115.7 Hz and 227.4 Hz | Boutin, Fletcher, Smith and Wolfe, SMAC 2013 |
Context note: the low Bb2 sounded above its bore peak and the Bb3 just below it, which is why acousticians treat the impedance curve as a map of where notes are easy, not a list of exact pitches. Most recent available data for these trombone peak measurements: SMAC conference, 2013.
2. Bells, Hands and Vent Holes: Reshaping the Peaks
The bell also sets the cutoff frequency, the point above which sound no longer reflects back to the lips and simply radiates out. Above it the impedance peaks shrink and the instrument loses its grip on the player. That is why a horn player’s right hand matters so much: without a hand in the bell, earlier measurements found horn impedance peaks greatly reduced above 450 Hz and gone above 750 Hz, as summarised by Dell, James, Davidson and Wolfe at ISMA 2010.
Side holes do the same job from a different place. A 2025 study of a baroque-style vented trumpet measured how a single open hole moves the resonances nearest the notes it is meant to fix (Arago Bishop, Myers and Campbell, Forum Acusticum 2025). The lesson from both: small geometry changes near the open end move peaks by a few hertz and change their height, and players notice.
| Metric | Value | Source |
|---|---|---|
| Horn impedance peaks with no hand in the bell (earlier measurements by Backus, Benade and Widholm) | Greatly reduced above 450 Hz, absent above 750 Hz | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Cutoff frequency of the horn bell | Around 500 Hz | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Spread between repeated measurements of horn impedance peaks 1 to 20, same replica hand reinserted (rms) | 0.1 dB in height and 0.4 Hz in frequency | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Horn players who rated the practice mute closest to the hand’s harmonicity as in tune | 4 of the 5 who answered | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Cutoff frequency of the small octave vent hole (1.75 mm radius) on a vented trumpet | 817 Hz | Arago Bishop, Myers and Campbell, Forum Acusticum 2025 |
| Resonance nearest the note G5, all holes closed vs thumb hole open | 790.30 Hz vs 829.19 Hz | Arago Bishop, Myers and Campbell, Forum Acusticum 2025 |
Outlier note: a vent hole acts like a high-pass filter. Resonances below its cutoff are pushed around strongly and resonances above it barely change, which is why the small octave hole, with its low cutoff, disturbs the resonances near its notes far less than the large thumb hole, whose cutoff of about 1913 Hz sits well above the notes it serves. Most recent available data on hand position in the horn bell: ISMA, 2010.
3. Mouthpiece Cup, Throat and Backbore
The mouthpiece is a small resonator attached to a large one. Its cup volume behaves like a spring (an acoustic compliance) and its narrow throat like a mass (an inertance), so together they resonate, which is why the mouthpiece significantly raises trumpet input impedance across 200 Hz to 1.5 kHz, the instrument’s normal playing range (Moore, Acoustics Today 2016). A shallower cup raises that resonance, which is why players often switch to one when they need notes above the normal range.
Modelling backs up what players hear. A finite element study of a trumpet, cornet and flugelhorn found each mouthpiece left a distinct peak in the pressure spectrum at the mouthpiece, and that the mouthpiece, more than the tubing, shaped the mid-range (Rose and Holloway, Acoustics 2012). The backbore myth fares worse: a doctoral study found shape, not total volume, tracked timbre (Frost, University of Washington 2014).
| Metric | Value | Source |
|---|---|---|
| Simulated pressure peak at the mouthpiece: trumpet, cornet, flugelhorn | Around 790 Hz, 660 Hz and 1150 Hz | Rose and Holloway, Acoustics 2012 |
| Flugelhorn second harmonic in simulation, own mouthpiece vs trumpet mouthpiece (share of the dominant peak) | Around 20% vs 75% | Rose and Holloway, Acoustics 2012 |
| Measured tubing bore diameter: trumpet, cornet, flugelhorn | 11.66 mm, 11.68 mm and 10.50 mm | Rose and Holloway, Acoustics 2012 |
| Mouthpieces owned by professional brass players | 3 to 10 | Moore, Acoustics Today 2016 |
| Backbores copied and tested, players, test pitches | 12 backbores, 5 trumpet players, 233 Hz, 466 Hz and 932 Hz | Frost, University of Washington DMA thesis 2014 |
| Link between total backbore volume and timbre vs backbore shape and timbre | Only moderate at some pitches vs strong | Frost, University of Washington DMA thesis 2014 |
Context note: in the studio recordings of the same three instruments, the dominant harmonic of a sustained F4 (349 Hz) was the third for both trumpet and cornet and the first for the flugelhorn (Rose and Holloway, Acoustics 2012). Most recent available data: 2012 to 2014; no newer controlled mouthpiece study with published numbers turned up in our search.
4. Lip Vibration and Mouth Pressure
The lips are a valve that the air column partly controls. Players set the pressure and the embouchure, but the impedance peak decides where the buzz settles, and a skilled player can lean the note either side of it. Ten trombonists normally played about 1.1% above the frequency of the bore impedance peak, and could bend below and above it without a discontinuity (Boutin, Fletcher, Smith and Wolfe, JASA 2015). The player’s own airway mostly stays out of the way: vocal tract impedance peaks were usually much smaller than the bore’s and became comparable only above about 1 kHz in a seven-player trumpet study (Chen, Smith and Wolfe, JASA 2012).
The pressures involved are large for a body to produce on purpose. A three-player trumpet study found maximum pressures between about 7 kPa and 15 kPa, and about 25 kPa on the highest notes (Fletcher and Tarnopolsky, JASA 1999). Force at the rim climbs too: the newest data, on French horn, show average pressing force rising eightfold from low F2 to high F5 (Hirano and Kinoshita, JASA 2026).
| Metric | Value | Source |
|---|---|---|
| Blowing pressure on the highest trumpet notes (one of three players) | About 25 kPa | Fletcher and Tarnopolsky, JASA 1999 |
| Maximum blowing pressure of the other two trumpet players | About 7 kPa and about 15 kPa | Fletcher and Tarnopolsky, JASA 1999 |
| Rise in minimum (threshold) blowing pressure per hertz of note frequency, by player | About 4 to 8 Pa per Hz | Fletcher and Tarnopolsky, JASA 1999 |
| Mouth pressure jump at a sharp mezzo-forte F4 attack vs a soft piano attack | Almost 2 kPa vs less than 1 kPa | Hruska, Svejda and Gustar, Vienna Talk 2015 |
| Initial blow-off pressure before a soft trumpet note starts | About 250 Pa | Hruska, Svejda and Gustar, Vienna Talk 2015 |
| Average mouthpiece lip-pressing force, 11 professional horn players, F2 vs F5 at mezzo-forte | 5 N vs 40 N | Hirano and Kinoshita, JASA 2026 |
| Range of lip-pressing force between players at F5 | 16 N to 73 N | Hirano and Kinoshita, JASA 2026 |
| Margin force (pressing beyond the minimum needed to play) as a share of total force | 35% to 57% | Hirano and Kinoshita, JASA 2026 |
Context note: the attack transients come from one semi-professional player filmed at 12,000 frames per second through a glass mouthpiece, so treat them as pilot values (Hruska, Svejda and Gustar, Vienna Talk 2015). Most recent available data on trumpet blowing pressure: JASA, 1999. The comparison between buzzing lips and vibrating vocal folds has become a research line of its own, a useful companion to our singing voice synthesis pitch accuracy statistics.
5. Sound Levels: From the Bell to the Player’s Ears
Brass instruments are inefficient converters of breath into sound, yet they are among the loudest acoustic instruments in an orchestra. High trumpet notes reached a maximum A-weighted level of about 110 dB at 1 m, and below saturation each doubling of blowing pressure added about 15 dB (Fletcher and Tarnopolsky, JASA 1999). Past saturation, doubling the pressure buys only about 3 dB, which is why the last notch of fortissimo costs players so much effort.
The person most exposed is the player and whoever sits in front of the bell. Personal dosimeters on a student orchestra put the trumpeter above everyone else (Backus, Clark and Williamon, International Symposium on Performance Science 2007); our musician hearing loss and noise exposure statistics and orchestra pit acoustic shield statistics cover what that does to hearing and how pits try to contain it.
| Metric | Value | Source |
|---|---|---|
| Maximum A-weighted level of high trumpet notes at 1 m | About 110 dB | Fletcher and Tarnopolsky, JASA 1999 |
| Level gained per doubling of blowing pressure, normal range vs saturation | About 15 dB vs about 3 dB | Fletcher and Tarnopolsky, JASA 1999 |
| Average 8-hour daily dose (LEP,d), student trumpeter vs double bassist | 88.4 dB(A) vs 77.1 dB(A) | Backus, Clark and Williamon, ISPS 2007 |
| Trumpeter’s loudest day, as an 8-hour equivalent | 90.2 dB(A) | Backus, Clark and Williamon, ISPS 2007 |
| Trombonist’s loudest day, as an 8-hour equivalent | 85.3 dB(A) | Backus, Clark and Williamon, ISPS 2007 |
| Musicians whose loudest day exceeded the UK upper action level of 85 dB(A) | 7 of 10 | Backus, Clark and Williamon, ISPS 2007 |
| Impulses above 120 dB(C) in one week, trumpeter vs timpanist | 305 vs 319 | Backus, Clark and Williamon, ISPS 2007 |
Outlier note: LEP,d is the noise dose averaged over an 8-hour working day, and seating matters as much as instrument: a cellist placed in front of the brass section logged 87.9 dB(A) on one day, 2.6 dB more than the trombonist in the same rehearsal. Most recent available data for this player-by-player dosimetry: ISPS, 2007.
6. Nonlinear Propagation and Brassiness
Brassiness is the hard, bright edge a trumpet or trombone gains at high volume, and it comes from the air column rather than from the lips changing their buzz. At high pressure the louder parts of the wave travel slightly faster than the quieter parts, so the waveform steepens down long narrow tubing until it becomes a near-instantaneous pressure jump, a shock wave. In a trombone played fortissimo, this produces significant upper harmonics at frequencies that can extend beyond 40 kHz (Campbell and Myers, Forum Acusticum 2023).
How far a bore can push this is captured by the brassiness potential B, computed from the bore diameters along the tube relative to its narrowest point. High values mean long narrow sections and a bright fortissimo; gradually widening, conical bores score low and stay mellow (Myers, Pyle, Gilbert and Campbell, Vienna Talk 2010).
| Metric | Value | Source |
|---|---|---|
| During a crescendo: rise of the fundamental vs rise of the ninth and higher harmonics | 8 dB vs more than 45 dB | UNSW Music Acoustics, Brass acoustics introduction |
| Brassiness potential B: tenor sackbut, tenor trombone, bass trombone | 0.76, 0.70 and 0.70 | Myers, Pyle, Gilbert and Campbell, Vienna Talk 2010 |
| Brassiness potential B: saxhorn basse, tuba, ophicleide | 0.48, 0.39 and 0.30 | Myers, Pyle, Gilbert and Campbell, Vienna Talk 2010 |
| Effect of narrowing the whole bore by 25% | Equivalent to raising B by 10% | Myers, Pyle, Gilbert and Campbell, Vienna Talk 2010 |
Context note: musicians call narrow-bore instruments brighter even at the same B, and the simulations suggest why: a narrow bore needs more pressure at the mouthpiece to reach the same loudness, so it distorts sooner. The authors describe the 25%-for-10% equivalence as an initial ballpark figure that needs further testing. Most recent available B values: Vienna Talk, 2010.
7. Wall Vibration, Lacquer and Surface Finish
Players have long insisted the metal itself matters, and physicists long doubted it. The evidence now splits the difference. Damping the bell of a modern trumpet shifted the relative power of the fundamental by more than 3 dB (Moore, Shirley, Codrey and Daniels, Acta Acustica 2005), and later work traced much of the effect to the bell wall flexing with the air pressure inside, an effect strongest where the walls flare (Kausel, Zietlow and Moore, JASA 2010).
Finish is a smaller lever than folklore suggests. A 1997 bell-flare experiment found lacquer made no significant difference at a soft playing level and a difference only at a loud one (Pyle, Acoustical Society of America 133rd meeting 1997). A 2026 pilot with three same-model trumpets went further: players perceived bigger differences when they could see the finish, while the recorded sound barely changed (Oehler, Brandt and Reuter, Forum Acusticum 2026).
| Metric | Value | Source |
|---|---|---|
| Change in input impedance from damping bell vibrations | Up to 5% | Moore, Gorman, Rokni, Kausel and Chatziioannou, JASA 2015 |
| Change in the acoustic transfer function from axial bell vibrations | About 1 dB | Moore, Gorman, Rokni, Kausel and Chatziioannou, JASA 2015 |
| Young’s modulus (stiffness) of brass used in the wall-vibration model | About 100-125 GPa | Kausel, Zietlow and Moore, Vienna Talk 2010 |
| Rating dimensions where trumpets differed more when the finish was visible | 11 of 13 | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
| Share of acoustic feature variance tied to finish vs player vs unexplained (residual) | 0.43% vs 5.22% vs 94.35% | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
| Pairwise trumpet contrasts with a large effect size (d of 0.8 or more), visible vs blindfolded | 12 vs 5 | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
| Note-level recordings and acoustic features analysed | 1033 notes, 133 features | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
Context note: the 2026 study used one instrument per finish and ten players, so finish and individual instrument cannot be separated, and the authors call it exploratory. Most recent available bell-vibration measurements: 2005 and 2015.
Summary: Brass Instrument Mouthpiece & Bore Impedance by the Numbers
| Metric | Value | Source |
|---|---|---|
| Blowing pressure on the highest trumpet notes | About 25 kPa | Fletcher and Tarnopolsky, JASA 1999 |
| Trombonists’ playing frequency relative to the bore impedance peak | About 1.1% above | Boutin, Fletcher, Smith and Wolfe, JASA 2015 |
| Horn impedance peaks without a hand in the bell | Greatly reduced above 450 Hz, absent above 750 Hz | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Cutoff frequency of the horn bell | Around 500 Hz | Dell, James, Davidson and Wolfe, ISMA 2010 |
| Simulated mouthpiece pressure peak: trumpet, cornet, flugelhorn | Around 790 Hz, 660 Hz and 1150 Hz | Rose and Holloway, Acoustics 2012 |
| Flugelhorn second harmonic, own vs trumpet mouthpiece (simulation) | Around 20% vs 75% | Rose and Holloway, Acoustics 2012 |
| Dominant harmonic of a sustained F4: trumpet and cornet vs flugelhorn | Third vs first | Rose and Holloway, Acoustics 2012 |
| Link between total backbore volume and timbre vs backbore shape and timbre | Only moderate at some pitches vs strong | Frost, University of Washington DMA thesis 2014 |
| Average horn lip-pressing force, F2 vs F5 at mezzo-forte | 5 N vs 40 N | Hirano and Kinoshita, JASA 2026 |
| Range of horn lip-pressing force between players at F5 | 16 N to 73 N | Hirano and Kinoshita, JASA 2026 |
| Margin force as a share of total lip-pressing force | 35% to 57% | Hirano and Kinoshita, JASA 2026 |
| Mouth pressure jump at a sharp vs soft trumpet attack | Almost 2 kPa vs less than 1 kPa | Hruska, Svejda and Gustar, Vienna Talk 2015 |
| Average 8-hour daily dose, student trumpeter vs double bassist | 88.4 dB(A) vs 77.1 dB(A) | Backus, Clark and Williamon, ISPS 2007 |
| Brassiness potential B, tenor sackbut vs ophicleide | 0.76 vs 0.30 | Myers, Pyle, Gilbert and Campbell, Vienna Talk 2010 |
| Fundamental’s relative power shift when the trumpet bell is damped | More than 3 dB | Moore, Shirley, Codrey and Daniels, Acta Acustica 2005 |
| Young’s modulus of brass used in the wall-vibration model | About 100-125 GPa | Kausel, Zietlow and Moore, Vienna Talk 2010 |
| Share of acoustic feature variance tied to finish vs player | 0.43% vs 5.22% | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
| Rating dimensions with bigger trumpet differences when the finish was visible | 11 of 13 | Oehler, Brandt and Reuter, Forum Acusticum 2026 |
Methodology and Sources
We ran targeted searches across impedance, mouthpiece, lip, sound level, brassiness and wall vibration topics, then read each paper, thesis record or proceedings PDF directly. Every figure above was taken from the document itself; figures seen only in search summaries were dropped. Brass acoustics moves slowly, so several core measurements are older than three years and are flagged in their sections.
- Fletcher and Tarnopolsky, Blowing pressure, power, and spectrum in trumpet playing, JASA 1999
- Boutin, Fletcher, Smith and Wolfe, Relationships between pressure, flow, lip motion, and upstream and downstream impedances for the trombone, JASA 2015
- Boutin, Fletcher, Smith and Wolfe, Lip motion, the playing frequency of the trombone and the upstream and downstream impedances, SMAC 2013
- Chen, Smith and Wolfe, Do trumpet players tune resonances of the vocal tract?, JASA 2012
- Dell, James, Davidson and Wolfe, The effect of hand and mute on the impedance spectra of the horn, ISMA 2010
- UNSW Music Acoustics (Wolfe), Brass instrument (lip reed) acoustics: an introduction
- Moore, The Acoustics of Brass Musical Instruments, Acoustics Today 2016
- Moore, Shirley, Codrey and Daniels, The effects of bell vibrations on the sound of the modern trumpet, Acta Acustica united with Acustica 2005
- Moore, Gorman, Rokni, Kausel and Chatziioannou, Axial vibrations of brass wind instrument bells and their acoustical influence: Experiments, JASA 2015
- Kausel, Zietlow and Moore, Influence of wall vibrations on the sound of brass wind instruments, JASA 2010
- Kausel, Zietlow and Moore, Transmission line modeling of acoustical systems with vibrating walls, Vienna Talk 2010
- Myers, Pyle, Gilbert and Campbell, The influence of bore size on brassiness potential, Vienna Talk 2010
- Campbell and Myers, The contributions of Joel Gilbert to the understanding of brassiness, Forum Acusticum 2023
- Arago Bishop, Myers and Campbell, Acoustical behaviour of vent holes on brasswind instruments, Forum Acusticum 2025
- Oehler, Brandt and Reuter, Does the finish matter if no one is looking? Visual bias in trumpet testing, Forum Acusticum 2026
- Hirano and Kinoshita, Mouthpiece lip-pressing force and its component minimum and margin forces during French horn playing, JASA 2026
- Hruska, Svejda and Gustar, Transients of trumpet tone, Vienna Talk 2015
- Rose and Holloway, Finite element modeling of brass musical instruments, Acoustics 2012 (Australian Acoustical Society)
- Frost, Trumpet Mouthpiece Backbores: An Investigation of Interior Volume and Timbre, University of Washington DMA thesis 2014
- Pyle, How brass instruments are built: art, craft, perhaps even science, Acoustical Society of America 133rd meeting 1997
- Backus, Clark and Williamon, Noise exposure and hearing thresholds among orchestral musicians, International Symposium on Performance Science 2007
- Data watch: most measurements here come from small laboratory samples (three trumpeters for blowing pressure, one player for attack transients, ten players in the 2026 finish test), so treat them as well-documented examples rather than population averages. The 2010 horn paper reports the largest rms difference between replica hands as 0.8 dB and 0.6 Hz in its abstract but 0.6 dB and 1.3 Hz in its results section, so we quote neither as a headline. The mouthpiece effects in section 3 come from a linear simulation without a lip model, and the 2026 finish study is a preliminary conference manuscript that was not peer reviewed. The full journal version of the brassiness work (JASA 2012) and the original 1996 shock-wave paper were not openly readable, so their numbers are not used here; the reviewed Forum Acusticum 2026 proceedings and new JASA musical acoustics papers are the next data expected.
Last updated: November 7, 2026. We update this roundup quarterly, and the next refresh is expected when the final Forum Acusticum 2026 proceedings and the next Journal of the Acoustical Society of America musical acoustics papers are published.