Bore (wind instruments)
Encyclopedia
The bore of a wind instrument
is its interior chamber that defines a flow path through which air travels and is set into vibration to produce sounds. The shape of the bore has a strong influence on the instruments' timbre
.
s. These shapes affect the harmonics
associated with the timbre of the instrument. The conical bore has a timbre composed of odd and even harmonics, while the closed cylindrical bore or closed tube
is composed primarily of odd harmonics.
It should be noted that the harmonic characteristics of instruments such as the clarinet (closed cylinder) are more variable than a given waveform and bore alone not the only determining factor. The timbre of a clarinet, for instance, depending in the main on the construction of the mouthpiece which is neither a cone nor a cylinder and the properties of the reed. Furthermore, minute changes in air pressure and pressure applied to the reed modulate (vibrato, slurs) the tone.
(the fundamental
note) is approximately twice the length of the pipe. The wavelength produced by the second normal mode is half that, that is, the length of the pipe, so its pitch is an octave
higher; thus an open cylindrical bore instrument overblows
at the octave. This corresponds to the second harmonic, and generally the harmonic spectrum of an open cylindrical bore instrument is strong in both even and odd harmonics. For a stopped pipe, the wavelength produced by the first normal mode is approximately four times the length of the pipe. The wavelength produced by the second normal mode is one third that, i.e. the 4/3 length of the pipe, so its pitch is a twelfth higher; a stopped cylindrical bore instrument overblows at the twelfth. This corresponds to the third harmonic; generally the harmonic spectrum of a stopped cylindrical bore instrument, particularly in its bottom register, is strong in the odd harmonics only.
Instruments having a cylindrical, or mostly cylindrical, bore include:
of a cone. The wavelength produced by the first normal mode is approximately twice the length of the cone measured from the vertex. The wavelength produced by the second normal mode is half that, that is, the length of the cone, so its pitch is an octave higher. Therefore, a conical bore instrument, like one with an open cylindrical bore, overblows at the octave and generally has a harmonic spectrum strong in both even and odd harmonics.
Instruments having a conical, or approximately conical, bore include:
s deviate from a true cone or a cylinder. For example, although oboes and oboes d'amore are similarly pitched, they have differently shaped terminal bells. Accordingly, the voice of the oboe is described as "piercing" as compared to the more "full" voice of the oboe d'amore.
Although the bore shape of woodwind instruments generally determines their timbre, the instruments' exterior geometry typically has little effect on their voice. In addition, the exterior shape of woodwind instruments may not overtly match the shape of their bores. For example, while oboes and clarinets may outwardly appear similar, oboes have a conical bore while clarinets have a cylindrical bore.
s also are sometimes categorized as conical or cylindrical, though most in fact have cylindrical sections between a conical section (the mouthpiece
taper or leadpipe
) and a non-conical, non-cylindrical flaring section (the bell). Benade gives the following typical proportions:
These proportions vary as valves or slides are operated; the above numbers are for instruments with the valves open or the slide fully in. Therefore the normal mode frequencies of brass instruments do not correspond to integer multiples of the first mode. However, players of brasses (in contrast to woodwinds) are able to "lip" notes up or down substantially, and to make use of certain privileged frequencies in addition to those of the normal modes, to obtain in-tune notes.
Wind instrument
A wind instrument is a musical instrument that contains some type of resonator , in which a column of air is set into vibration by the player blowing into a mouthpiece set at the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of...
is its interior chamber that defines a flow path through which air travels and is set into vibration to produce sounds. The shape of the bore has a strong influence on the instruments' timbre
Timbre
In music, timbre is the quality of a musical note or sound or tone that distinguishes different types of sound production, such as voices and musical instruments, such as string instruments, wind instruments, and percussion instruments. The physical characteristics of sound that determine the...
.
Bore shapes
The cone and the cylinder are the two idealized shapes used to describe the bores of wind instrumentWind instrument
A wind instrument is a musical instrument that contains some type of resonator , in which a column of air is set into vibration by the player blowing into a mouthpiece set at the end of the resonator. The pitch of the vibration is determined by the length of the tube and by manual modifications of...
s. These shapes affect the harmonics
Harmonic series (music)
Pitched musical instruments are often based on an approximate harmonic oscillator such as a string or a column of air, which oscillates at numerous frequencies simultaneously. At these resonant frequencies, waves travel in both directions along the string or air column, reinforcing and canceling...
associated with the timbre of the instrument. The conical bore has a timbre composed of odd and even harmonics, while the closed cylindrical bore or closed tube
Closed tube
In the field of acoustics, a tone is created by the periodic vibrations of air applied to a resonator. There are several ways in music to create such vibrations. One of these is to use a closed tube and to blow across the end. This creates a Bernoulli, or "siphon", effect just below the open end or...
is composed primarily of odd harmonics.
It should be noted that the harmonic characteristics of instruments such as the clarinet (closed cylinder) are more variable than a given waveform and bore alone not the only determining factor. The timbre of a clarinet, for instance, depending in the main on the construction of the mouthpiece which is neither a cone nor a cylinder and the properties of the reed. Furthermore, minute changes in air pressure and pressure applied to the reed modulate (vibrato, slurs) the tone.
Cylindrical bore
The diameter of a cylindrical bore remains constant along its length. The acoustic behavior depends on whether the instrument is stopped (closed at one end and open at the other), or open (at both ends). For an open pipe, the wavelength produced by the first normal modeNormal mode
A normal mode of an oscillating system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. The frequencies of the normal modes of a system are known as its natural frequencies or resonant frequencies...
(the fundamental
Fundamental frequency
The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the lowest frequency of a periodic waveform. In terms of a superposition of sinusoids The fundamental frequency, often referred to simply as the fundamental and abbreviated f0, is defined as the...
note) is approximately twice the length of the pipe. The wavelength produced by the second normal mode is half that, that is, the length of the pipe, so its pitch is an octave
Octave
In music, an octave is the interval between one musical pitch and another with half or double its frequency. The octave relationship is a natural phenomenon that has been referred to as the "basic miracle of music", the use of which is "common in most musical systems"...
higher; thus an open cylindrical bore instrument overblows
Overblowing
Overblowing A technique used while playing a wind instrument which, primarily through manipulation of the supplied air , causes the sounded pitch to jump to a higher one...
at the octave. This corresponds to the second harmonic, and generally the harmonic spectrum of an open cylindrical bore instrument is strong in both even and odd harmonics. For a stopped pipe, the wavelength produced by the first normal mode is approximately four times the length of the pipe. The wavelength produced by the second normal mode is one third that, i.e. the 4/3 length of the pipe, so its pitch is a twelfth higher; a stopped cylindrical bore instrument overblows at the twelfth. This corresponds to the third harmonic; generally the harmonic spectrum of a stopped cylindrical bore instrument, particularly in its bottom register, is strong in the odd harmonics only.
Instruments having a cylindrical, or mostly cylindrical, bore include:
- ClarinetClarinetThe clarinet is a musical instrument of woodwind type. The name derives from adding the suffix -et to the Italian word clarino , as the first clarinets had a strident tone similar to that of a trumpet. The instrument has an approximately cylindrical bore, and uses a single reed...
(stopped) - FluteFluteThe flute is a musical instrument of the woodwind family. Unlike woodwind instruments with reeds, a flute is an aerophone or reedless wind instrument that produces its sound from the flow of air across an opening...
(Boehm systemBoehm SystemThe Boehm system is a system of keywork for the flute, created by inventor and flautist Theobald Boehm between 1831 and 1847.Prior to the development of the Boehm system, flutes were most commonly made of wood, with an inverse conical bore, eight keys, and tone holes that were small in size, and...
— open) - SudrophoneSudrophoneThe sudrophone is a brass instrument invented by François Sudre in Paris, its shape resembling that of an ophicleide. It was patented in 1892. It has a cylindrical bore and four Perinet valves. Its length is 86 cm and the bell diameter is 17 cm...
Conical bore
The diameter of a conical bore varies linearly with distance from the end of the instrument. A complete conical bore would begin at zero diameter—the cone's vertex. However, actual instrument bores approximate a frustumFrustum
In geometry, a frustum is the portion of a solid that lies between two parallel planes cutting it....
of a cone. The wavelength produced by the first normal mode is approximately twice the length of the cone measured from the vertex. The wavelength produced by the second normal mode is half that, that is, the length of the cone, so its pitch is an octave higher. Therefore, a conical bore instrument, like one with an open cylindrical bore, overblows at the octave and generally has a harmonic spectrum strong in both even and odd harmonics.
Instruments having a conical, or approximately conical, bore include:
- BassoonBassoonThe bassoon is a woodwind instrument in the double reed family that typically plays music written in the bass and tenor registers, and occasionally higher. Appearing in its modern form in the 19th century, the bassoon figures prominently in orchestral, concert band and chamber music literature...
- CornetCornetThe cornet is a brass instrument very similar to the trumpet, distinguished by its conical bore, compact shape, and mellower tone quality. The most common cornet is a transposing instrument in B. It is not related to the renaissance and early baroque cornett or cornetto.-History:The cornet was...
- EuphoniumEuphoniumThe euphonium is a conical-bore, tenor-voiced brass instrument. It derives its name from the Greek word euphonos, meaning "well-sounding" or "sweet-voiced"...
- FlugelhornFlugelhornThe flugelhorn is a brass instrument resembling a trumpet but with a wider, conical bore. Some consider it to be a member of the saxhorn family developed by Adolphe Sax ; however, other historians assert that it derives from the valve bugle designed by Michael Saurle , Munich 1832 , thus...
- FluteFluteThe flute is a musical instrument of the woodwind family. Unlike woodwind instruments with reeds, a flute is an aerophone or reedless wind instrument that produces its sound from the flow of air across an opening...
(pre-Boehm) - OboeOboeThe oboe is a double reed musical instrument of the woodwind family. In English, prior to 1770, the instrument was called "hautbois" , "hoboy", or "French hoboy". The spelling "oboe" was adopted into English ca...
- SaxophoneSaxophoneThe saxophone is a conical-bore transposing musical instrument that is a member of the woodwind family. Saxophones are usually made of brass and played with a single-reed mouthpiece similar to that of the clarinet. The saxophone was invented by the Belgian instrument maker Adolphe Sax in 1846...
- TubaTubaThe tuba is the largest and lowest-pitched brass instrument. Sound is produced by vibrating or "buzzing" the lips into a large cupped mouthpiece. It is one of the most recent additions to the modern symphony orchestra, first appearing in the mid-19th century, when it largely replaced the...
- Uilleann pipesUilleann pipesThe uilleann pipes or //; ) are the characteristic national bagpipe of Ireland, their current name, earlier known in English as "union pipes", is a part translation of the Irish-language term píobaí uilleann , from their method of inflation.The bag of the uilleann pipes is inflated by means of a...
Woodwinds
Sections of the bores of woodwind instrumentWoodwind instrument
A woodwind instrument is a musical instrument which produces sound when the player blows air against a sharp edge or through a reed, causing the air within its resonator to vibrate...
s deviate from a true cone or a cylinder. For example, although oboes and oboes d'amore are similarly pitched, they have differently shaped terminal bells. Accordingly, the voice of the oboe is described as "piercing" as compared to the more "full" voice of the oboe d'amore.
Although the bore shape of woodwind instruments generally determines their timbre, the instruments' exterior geometry typically has little effect on their voice. In addition, the exterior shape of woodwind instruments may not overtly match the shape of their bores. For example, while oboes and clarinets may outwardly appear similar, oboes have a conical bore while clarinets have a cylindrical bore.
Brasses
Brass instrumentBrass instrument
A brass instrument is a musical instrument whose sound is produced by sympathetic vibration of air in a tubular resonator in sympathy with the vibration of the player's lips...
s also are sometimes categorized as conical or cylindrical, though most in fact have cylindrical sections between a conical section (the mouthpiece
Mouthpiece (brass)
On brass instruments the mouthpiece is the part of the instrument which is placed upon the player's lips. The purpose of the mouthpiece is a resonator, which passes vibration from the lips to the column of air contained within the instrument, giving rise to the standing wave pattern of vibration in...
taper or leadpipe
Leadpipe
In a brass instrument, a leadpipe is the pipe or tube into which the mouthpiece is placed.For example, on the illustration of a trombone, the leadpipe would be between #3 and #4, the mouthpiece and the slide lock ring. In the illustration of a French horn, the leadpipe is #2.Some instruments have a...
) and a non-conical, non-cylindrical flaring section (the bell). Benade gives the following typical proportions:
| Trumpet | Trombone | Horn | |
|---|---|---|---|
| Mouthpiece taper | 21% | 9% | 11% |
| Cylindrical part | 29% | 52% | 61% |
| Bell | 50% | 39% | 28% |
These proportions vary as valves or slides are operated; the above numbers are for instruments with the valves open or the slide fully in. Therefore the normal mode frequencies of brass instruments do not correspond to integer multiples of the first mode. However, players of brasses (in contrast to woodwinds) are able to "lip" notes up or down substantially, and to make use of certain privileged frequencies in addition to those of the normal modes, to obtain in-tune notes.