NOTE: all the trumpet sound samples were performed by Francesco Gibellini on 26/10/2007. Sound engineer: Valerio Carboni.

Structure of the instrument

Trumpet in C "exploded" view

The modern trumpet consists of a cup-shaped mouthpiece, inserted into a cylindrical metal tube wound in a spiral, which ends in a conical bell. Halfway along the main tube, small additional portions of tubing are connected; they can be isolated, or used as extensions of the main tube, by means of a mechanism of piston valves (see below). The trumpets of antiquity had no pistons, and had a straight tube (sometimes actually made of cane) or, at most, one bent into an "S". The modern form of the trumpet relies on two substantial technological skills: the technique of carefully bending metal tubes, perfected in the West only between the 15th and 16th centuries; the mechanism of piston valves, invented in 1814 by Blühmel and Stölzel, and perfected in 1839 by Périnet.

How the sound is produced

The source of the oscillations

• In all brass instruments the primary source of the oscillation is the player's lips, driven by the breath. The mouthpiece of the instrument makes their oscillation easier, and channels the pressure wave generated into the resonating tube.
• The fundamental resonance frequency of the lips must normally correspond to the resonance frequency of the tube, because the coupling between the lips and the air in the sound tube is rather weak. However, the resonance frequency of the whole system can be adjusted by the player by changing the tension of the lips.
• A greater tension corresponds to a greater elastic constant, and therefore to a higher oscillation frequency.

For a practical illustration of what is set out in this section, see the sound examples in the sections blowing is not enough and The sound of the trumpet... without the trumpet

Mouthpiece	Lips and mouthpiece

Intonation

As in all wind instruments, the sound produced by the trumpet is essentially determined by the natural resonances of the tube. There are therefore only two ways of producing several distinct sounds:

1. changing the (real or effective) length of the tubing
2. with the length fixed, selecting a particular normal mode of the tube.

Of these two methods, only the second was used from the most remote times until the modern era. Modern piston valves were invented only at the beginning of the 19th century.

The natural trumpet

The trumpet is an instrument born in the mists of time, especially for military use. Indeed, thanks to the high power and clarity of the sounds it can produce, it was particularly suited to transmitting simple, recognizable signals over long distances (and above background noise), as happened on battlefields before the modern era. The ancient trumpet is therefore the "natural" one, without keys. With this instrument it is not possible to obtain all the sounds of the modern scale, but only the harmonics of a given fundamental. For this reason one speaks of a "trumpet in B♭" or a "trumpet in C", etc., depending on its size, meaning that it can produce only the natural harmonic sounds of B♭, or those of C, etc. The name has then remained for modern piston trumpets too but, in this case, it has more to do with the problem of transposition (see below).

The introduction of pistons

Detail of the pistons of a trumpet in C

Before the invention of valves there were only two ways of changing the pitch of the fundamental of a trumpet:

1. changing trumpet, or
2. removing a movable part at the end of the tubing (the slide), and replacing it with a longer one.

In any case, short of continually changing instrument, it was never possible to produce all the notes of the chromatic scale. For this reason, in a Baroque orchestra the trumpet generally has parts that are much less complex and melodic than those of the string instruments, based on a few fundamental degrees of the scale.

The introduction of valves and pistons, around the middle of the 19th century, instead opened the door to the full release of the instrument's potential.

If you look at the photographs, however, you will notice that, while the flute, the clarinet and the oboe have many keys available for this function, the trumpet has only three (and the natural trumpet none). The same holds for many other brass instruments such as the trombone, the horn, etc.

How, then, is it possible to play all the notes at will?

As said at the beginning, intonation is the result of two synchronized actions:

1. the three keys act in combination with each other, and increase the (real) length of the tubing by connecting to the main tube some small curved detours (the tangle of tubes under the keys). Each key adds a section of extra tubing that lowers the fundamental frequency of the main tube.
   • The first key lowers it by a tone (two semitones)
   • the second key lowers it by a semitone
   • the third key lowers it by a tone and a semitone (three semitones)

   The possible combinations therefore give seven notes starting from a single fundamental.

2. To play other notes besides the previous seven, the player must change the setting of the lips so as to excite a higher mode of the tube. That is, the player must change the fundamental, and on this new fundamental can again act with the keys to obtain another seven notes. Given a fundamental, its harmonics are obtained by changing the position and the tension of the lips and forcing them to oscillate at the resonance frequency of the desired note (see the sound examples in Intonation and harmonic sounds).

Transposition

The trumpet belongs to the class of transposing instruments: these are all the instruments that exist in several varieties, identical except for their size. They all read transposed staves, so as to be able to use the same fingering relative to their different fundamentals.

Let us clarify with an example.

The problem, in short, is the following: suppose we play a certain piece with a trumpet in C. At some point we want to play the same piece, but with a trumpet in B♭. The problem is that now the same fingerings we used on the trumpet in C produce completely different notes; in particular, notes a tone lower. To make it easier to play a piece, the idea was therefore to transpose the notation, instead of leaving the mental operation of transposing the fingering to the player. The same piece written for a trumpet in C, therefore, looks completely different when it is written (transposed) for a trumpet in B♭. On the other hand, two players reading the same staff with two different trumpets need make no effort to transpose the music: they play exactly the same fingering, and the instrument naturally sounds at two different pitches.

In short:

• when the trumpet in C reads C, it plays C, reads D and plays D, etc.
• while a trumpet in B♭ that reads C (and fingers it in the same way as the colleague with the trumpet in C) actually plays B♭; it reads D and, without changing fingering, plays C, etc.

How the timbre is formed

The sound of the trumpet originates from the buzzing of the lips in the mouthpiece, which produces an approximately triangular wave, rich in harmonics (see the sound of the trumpet... without the trumpet). The bore does not only determine the pitch of the note: its resonances reinforce the components of the spectrum that fall close to them, and the shape of the mouthpiece and of the bell makes these resonances nearly harmonic.

The bell also has a second role: low-frequency waves are largely reflected back inwards at its mouth, while waves of higher frequency (above about 1500 Hz) get out more easily. The bell therefore acts as a high-pass filter for the radiated sound, and this contributes to the bright timbre of the instrument; for the same reason the high frequencies come out mainly in the direction of the bell (see directionality).

Finally, the timbre changes with loudness: when playing forte the pressure in the mouthpiece is so high that the wave becomes distorted as it propagates along the long cylindrical bore (nonlinear propagation), and the spectrum is enriched with high harmonics. This is why the sound of the trumpet is much more "brassy" in forte than in piano (see dynamic range).

Acoustic characteristics

Excerpts of live performance

A short improvisation was recorded in an almost reverberation-free environment with a microphone very close to the instrument. The sample faithfully corresponds to what is heard at a short distance from the instrument, but does not reproduce the listening conditions of a concert hall. The sound is very faithful to the original, but very "dry". The right and left channels are identical copies of the same signal.

waveform	spectrogram	Audio
		TR_SampleDry.mp3 Trumpet: ("dry" version)

A basic electronic manipulation of the sample consists in introducing dynamic compression of the sound, that is, automatically reducing the difference between the loudest and the softest sounds, so as to even out its dynamics. Note that now the right and left channels show small differences. The net effect is to introduce a "virtual" listening environment, which simulates a slightly reverberant real environment, and therefore reproduces more faithfully the sound that would be heard in a concert hall. The sound seems richer overall, although all the pitches and durations of the notes are unchanged with respect to the "dry" sample.

waveform	spectrogram	Audio
		TR_SAMPLE.mp3 Trumpet: (version with dynamic compression)

Intonation and harmonic sounds

Let us recall what was set out in the section on intonation in the trumpet: intonation is obtained through the correct and synchronized combination of the setting of the lips (able to select a particular harmonic sound for a given tube length) and the setting of the keys (able to obtain six other different tube lengths). In the following example two series of sounds can be heard. The first series corresponds to a tube length whose fundamental is B♭₃, while in the second the player has pressed the "-1 semitone" key, so the fundamental is A₃. Within each series, instead, the harmonics are obtained with the same key configuration, by means of the lips alone.

waveform	spectrogram	Audio
		TR_ArmoniciConTasti.mp3 Trumpet in B♭: natural harmonics, without and with the second key pressed

The most "natural" of harmonics

This example presents the range of natural harmonics of a trumpet without keys. Remember that the trumpet is tuned in C, that is, it can produce the natural harmonics of C. The different harmonics are produced by exciting the trumpet at the right frequency, tensing the lips and changing the pressure of the exhaled air. The higher harmonics therefore become progressively more and more difficult to produce.

waveform	spectrogram	Audio
		TR_NAT_Armonici.mp3 Natural trumpet: harmonics

Blowing is not enough

The sound of the trumpet is not produced by the simple flow of air in the tube, but by the regular oscillation of the air pressure, produced in turn by the oscillation of the lips. If you blow into a trumpet you do not get the sound we know, but only a hiss. However, by listening carefully to this hiss while the keys are pressed in succession, we can recognize the different resonances corresponding to the different tube lengths. In more technical terms, and looking at the sonogram, we can say that the noise of the different hisses is differently "coloured".

waveform	spectrogram	Audio
		TR_Soffio.mp3 Trumpet: hiss for different tube lengths

The sound of the trumpet... without the trumpet

With these two examples we want to highlight the role of the lips and of the mouthpiece.

We saw in the section on the source of the oscillations that "blowing" into the instrument is not enough. So we removed the instrument, keeping only the mouthpiece, and asked the player to play the mouthpiece as if the trumpet were also attached, and to play a short portion of a scale. The mouthpiece has a shape suited to making it easier for the lips to vibrate at different frequencies. From the analysis of the sonogram it is evident that the spectrum of the lips + mouthpiece system, which already has partial components in integer ratios (that is, harmonics), is also characterized by broad noise bands that are essentially independent of the note played. For example, the last note, a C₅ at about 522 Hz, has very clear lines at about 1044 Hz, 1566 Hz, etc., but also a band about 2 kHz wide around 2500 Hz, one about 4 kHz wide around 3 kHz, another 1600 Hz wide around 8100 Hz, etc. The noise bands are in turn in an approximate harmonic series with one another, and correspond to a fundamental around 2100 Hz.

waveform	spectrogram	Audio
		TR_Bocchino.mp3 Trumpet in B♭: mouthpiece only

Here is what can be heard using only the lips and a cut mouthpiece, so that its upper half is open. This sound comes close to what can be obtained with the lips alone. At the source of the trumpet's sound lies this kind of buzz, corresponding to an approximately triangular wave. One clearly sees, on the one hand, the importance of the correct setting of the lips for intonation and, on the other, of the resonant response of the tube (absent here) for the formation of the timbre.

waveform	spectrogram	Audio
		TR_Labbra.mp3 Trumpet: cut mouthpiece only (= lips only)

Special effects

As in the other wind instruments, in the trumpet special effects can be produced simply by pronouncing certain phonemes while playing the instrument. Pronouncing something like "ta-ga-ta-ga-ta-ga..." while playing a single steady note produces the so-called double tonguing. From the acoustic point of view, the voiceless alveolar "t" corresponds to a brief interruption of the sound, while the voiced velar "g" corresponds to a softer attenuation. The net effect depends on how fast the sequence is pronounced. In this case, examining the envelope in the time domain, one clearly distinguishes "ta" (the sound goes to zero) from "ga" (the sound is attenuated, but not to zero). The two-syllable "ta-ga" repeats at a frequency of about 5Hz.

waveform	spectrogram	Audio
		TR_DoppioStaccato.mp3 Trumpet: double tonguing ("ta-ga")

Pronouncing an "r" produces flutter-tonguing, similar to that obtained with the same device on the flute (see special effects on the flute). In this case, however, the apparent frequency of the flutter is higher (around 40 Hz, compared with about 25 Hz for the flute).

waveform	spectrogram	Audio
		TR_Frullo.mp3 Trumpet: flutter-tonguing ("r")

waveform	spectrogram	Audio
		TR_Tremolo.mp3 Trumpet: tremolo

The function of the tuning slide

Detail of the fully extended tuning slide on a trumpet in B♭

The tuning slide is the "U"-shaped curved part of tubing that closes the lower part of the tubing. It is removable, and can slide back and forth by a few cm, allowing the player to adjust the basic tuning of the instrument. This adjustment is indispensable when playing in an ensemble with other instruments. The frequency range covers about a semitone, and is not normally used to obtain glissando effects. An instrument that instead uses this technique for intonation is the slide trombone, in which the slide is much longer and under the direct control of the player, who however has no pistons to operate.

waveform	spectrogram	Audio
		TR_Glissato.mp3 Trumpet: glissando

Timbre and register

waveform	spectrogram	Audio
		TR_Ottave.mp3 Trumpet: C in three different octaves

Vibrato

As for the other instruments, vibrato is a very flexible expressive device, whose parameters are adapted each time by the player to the needs of the piece. In this example a rather evident amplitude modulation of about 3 dB at a frequency of about 6.2 Hz is observed, associated with a very small frequency modulation, which does not cause an appreciable shift of the fundamental, but is evident in the spectrogram in the small undulations of the higher harmonics.

waveform	spectrogram	Audio
		TR_Vibrato.mp3 Trumpet: vibrato

Other types of trumpet

Natural trumpet Trumpet in B♭ and in C

Besides trumpets of similar sizes, such as the trumpet in B♭ and the one in C, there are also instruments of completely different size, which therefore operate in a different register. This is the case of the piccolo trumpet, whose different range can be heard in this example. In this field, standardization towards a limited number of types was dictated by the need to have music that could be performed in the same way in different and distant places (for example by different orchestras). There are, however, notable examples in which exactly the opposite is desired, that is, that a certain piece can be played only by an instrument created specially for it. One example is the famous Triumphal March from G. Verdi's Aida, which is played precisely with the Aida trumpets. This happens when one wants to give the piece a "unique" timbral colour.

waveform
piccolo trumpet	trumpet in B♭
spectrogram	audio
	TR_DueTrombe.mp3 Piccolo and normal trumpet

Dynamic range

The trumpet is an instrument that can generate considerable acoustic power. For this reason it has always been used on battlefields to send intelligible signals over long distances. In this example the dynamic range of the peak covers about 18 dB, so adjust the volume so that it is not too loud. Of course the value averaged over a period is somewhat lower, but remember that the emitted power doubles every 3 dB, so in forte the instrument emits a sound power about 64 times greater than in piano.

waveform
spectrogram	audio
	TR_PianoForte.mp3 Trumpet: piano, forte

Attack time

In a sforzando, or in a crescendo like those recorded here, not only the amplitude but also the waveform changes drastically in time. By exploiting the wide dynamic range and the quick response of the instrument, sudden changes of "mood" can be achieved. Note in the figure of the envelope that the emission nevertheless needs a small initial impulse: the intensity grows rapidly in the first 30 hundredths of a second. Then the player chooses whether to keep increasing it, or to settle the sound on piano.

waveform !
wave envelope	spectrogram
Audio
TR_Sforzandi.mp3 Trumpet: hard attack ("sforzato"), and crescendo

Directionality

The trumpet is a particularly directional instrument. All the sound energy is radiated from the bell, unlike what happens in woodwinds, which always also have holes along the tube. But we know that, because of the phenomenon of diffraction (see also diffraction of sound), high frequencies are the most directional, while low frequencies tend to form spherical waves. It follows that by rotating the direction of emission, for example by asking the player to stand perpendicular to the microphone instead of pointing towards it, a considerable change in the perceived timbre will be obtained. In particular, as can be clearly seen both from the spectrogram and from the two time-averaged spectra, there is a strong attenuation of frequencies above about 6 kHz (corresponding to a wavelength in air of about 5.7 cm).

waveform
towards the mic.	perpendicular to the mic.
spectra
towards the mic.	perpendicular to the mic.
spectrogram	audio
	TR_DirezioneMicrofono.mp3 Trumpet: pointed towards the microphone, and perpendicular to the microphone

The mute

There are many varieties of trumpet mutes. Essentially anything that can be inserted into the bell changes the sound of the instrument, as shown by the following waveforms and spectra, all recorded while the trumpet emits an essentially steady sound. In the case of the "wah-wah" (or "ua-ua") mute, the mute completely covers the bell on the "u", and is instead "opened" to obtain the "a".

waveform	spectrum	Audio
trumpet without mute
		TR_Sordine1.mp3 Trumpet: without and with mute 1, 2, and "wah wah"
trumpet with mute 1
trumpet with mute 2
trumpet with "wah wah" mute

Baroque (transposing) mute
Baroque mute	Audio
	TR_Sordine3.mp3 Trumpet: without and with transposing mute

Musical features

Introduction – Traditional use

We usually tend to associate the sound of the trumpet with band contexts and fanfare-like articulation. This tendency is confirmed in many cases both in the classical literature (just think of the famous Triumphal March from G. Verdi's Aida) and in film music (who does not remember the ringing "motto" of Star Wars, by the American composer J. Williams?). Indeed, given its physical characteristics (and in particular thanks to the flare of the bell, which opens the spectrum to the highest harmonics), the resulting timbre easily takes on the ringing character we all know. Nevertheless, especially in the 20th century, with the evolution and refinement of its mechanics, the trumpet became a much more versatile instrument, able to fit into completely different musical contexts, or in any case ones that lend themselves to much more varied expressive nuances.

New explorations

The opening of G. Mahler's 5th symphony is a striking example: the notes repeated so insistently in the low register go well beyond the fanfare character, and sound rather like an ineluctable sentence, with no way out from the very beginning (the composer's own marking is Trauermarsch, that is, funeral march). We are plunged into a completely different atmosphere in the Marche du soldat that opens I. F. Stravinsky's Histoire du soldat, where the trumpet call projects us into a climate between the fairy-tale and the hallucinatory, through an extremely dry and essential language. Here the timbre of the instrument must be sharp and penetrating, far from any kind of gratuitous expressiveness. In Petrushka, Stravinsky himself uses the trumpet in three different ways within a few bars: first, in the Danse de la ballerine, together with the military drum, it performs an acrobatic solo ranging over all the registers of the instrument; immediately afterwards, in the 'Valse' of the Ballerina and the Moor, it sings, in a duet with the flute, with a larmoyant and perhaps somewhat grotesque expressiveness (the composer specifies "cantabile sentimentalmente"); finally, in the second part of the same piece it again takes on a markedly brilliant and virtuosic character.

Further reading and links

• We invite you to read the essential page Sound and resonance, where you will find the general principles of how a musical instrument works. Reading it will help you better appreciate the peculiarities of the instrument described on this page

• In our 2D Waves virtual laboratory you can experiment with the formation of reflected waves and their dependence on the shape of the "flare". The page experiments on sound tubes describes some guided experiments.