The Sound of Bells

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Glossary

I have put together this glossary to explain terms associated with bells and bell tuning which may be unfamiliar.

Acoustician
A harmless drudge, a searcher after new understanding.
Antinode
For a particular mode of vibration, a line around the bell parallel to the rim, or a line from rim to crown, where the amplitude of the vibration is maximum. See also nodal circle and nodal line.
Beats
A wobbling effect in a sound which contains two frequencies close together. Heard in bells with doublets.
Bourdon
A term often used for a heavy bell (e.g. several tons in weight).
Cent
A convenient way to measure intervals by the log of the frequency ratio. 100 cents make a semitone, 1200 cents make an octave. The interval in cents between two frequencies f1 and f2 is 1731.234 * ln (f2 / f1) where ln is the log to base e.
Clapper
The iron bar or striker, usually pivoted in the crown of the bell, which hits the soundbow to ring the bell. Usually has an enlarged portion called the ball which actually makes the impact.
Crown
The top of the bell.
Diatonic scale
The usual scale in western music, corresponding to the white notes on a keyboard.
Doublet
If a bell is not round, individual partials can split into a close pair of frequencies which beat together. Doublets can add antique charm to a bell's sound but are usually to be avoided.
Equal temperament
A way of tuning the diatonic scale such that all semitones are identical in size. Allows instruments to play in any key (and bells of a given note to be tuned to the same frequency whatever their position in the peal). Contrast with just tuning and meantone temperament.
Extra
An alternative name for the prime partial, most often used by Whitechapel.
Fundamental
In bell tuning, an alternative name for the prime partial. This name is not used by some on the grounds that, unlike in other instruments, the fundamental is not the lowest frequency partial of a bell.
Gilletts
The UK bell-founding firm of Gillett and Johnston, active from the late 19th to the middle 20th century. An early pioneer of true-harmonic tuning.
Hemony
The Hemony brothers, casting and tuning bells in the low countries in the 17th century, developed bell profiles and skill in true-harmonic tuning which are remarkable given the primitive equipment available to them.
Higher partials
The partials higher in frequency than the nominal.
Hum
The lowest of the five low partials of a bell.
Inner tuning
A term sometimes used to describe the tuning of the partials in a single bell (as opposed to outer tuning).
Just tuning
A way of tuning a diatonic scale for which, unlike equal and meantone temperament, all the frequencies are related by small whole numbers.
Low partials
The five partials of a bell lowest in pitch (hum, prime, tierce, quint and nominal) have the greatest effect on the timbre or quality of a bell's sound.
Meantone temperament
A way of tuning the diatonic scale which represents a compromise between equal temperament and just tuning. Various meantone temperaments were the most common way of tuning musical instruments for a couple of hundred years prior to the middle of the 19th century.
Missing fundamental
A psycho-acoustical effect whereby the ear creates a pitch for a musical sound which does not correspond to a partial frequency in the sound. See also virtual and spectral pitch.
Mode
A way in which a bell can vibrate and produce sound. Different vibrational modes have different nodal lines and circles. Different modes give rise to different partial frequencies in the bell's sound.
MP3
A way of compressing sound files on a computer to make them much smaller.
Nodal circle
A circle around the bell (i.e. parallel to the rim) which does not move for a particular mode of vibration. Different modes can have different numbers of nodal circles at different heights above the rim.
Nodal line
A line from rim to crown which does not move for a particular mode of vibration. Different modes can have different numbers of nodal lines around the bell - the number is always even.
Node
For a particular mode of vibration, a part of the bell which is stationary (or at least not moving in the plane of the vibration). See nodal line and nodal circle.
Nominal
The highest in frequency of the five low partials. Given this name because the strike note of a bell is usually about an octave below the nominal; hence this partial provides the note-name of the bell.
Pythagorean Tuning
Yet another tuning style (see just, equal and meantone) characterised by rather sharp thirds and sevenths. Thought suitable for melodic but not harmonic music.
Old style
A term used to describe bells which are not tuned on true-harmonic principles. UK old-style bells usually have hums which are sharp of true harmonic, and almost as often, primes which are flat of true-harmonic.
Octave nominal
The partial roughly an octave above the nominal.
Octave stretch
A way in which peals of bells (especially larger numbers) are tuned whereby the smaller bells are sharper than the diatonic scale would suggest they should be. Also seen in other instruments such as pianos.
Outer tuning
A term sometimes used to describe the tuning of a peal of bells together. See inner tuning.
Partial
An identifiable frequency in the sound of a bell, arising from a mode of vibration of the bell.
Peal
A set of bells, often between five and twelve in number, tuned to a diatonic scale.
Pitch
The note-name assigned by a listener to a bell or other musical sound.
Profile
The shape of a bell. Has a very significant effect on the timbre or sound quality of a bell. Intensity profile is something different; this is the term I use to describe the differing intensities of the various partials.
Prime
The second lowest of the five low partials of a bell. This partial is variously called the fundamental, the extra or the second partial.
Quint
One of the five low partials of a bell, very roughly a fifth above the prime. The quint has a nodal circle near the soundbow. Therefore, it is often quiet and hardly affects the timbre of the bell.
Rim partial
Strictly not a partial, but a mode of vibration in which there is an antinodal circle at or near the bell's rim. These modes of vibration are stimulated directly by the impact of the clapper, rather than receiving energy from other modes over time. Therefore, rim partials are of great importance in forming the strike note of a bell.
Secondary strike
An effect heard in large bells of a second strike note, often about a fourth above the first. The pitch of the secondary strike is often related to the eleventh partial (between nominal and superquint) and is probably due to the ear providing a missing fundamental related to the eleventh and other higher partials. See also virtual pitch.
Simpson
Canon A. B. Simpson, who wrote two pivotal papers on the sound of bells in the 1890s.
Simpson tuning
A common but erroneous term for true-harmonic tuning.
Soundbow
The lower part or rim of the bell.
Spectral pitch
The hearing by the ear of a pitch equal in frequency to one of the bell's partials. See also virtual pitch.
Splash
The sound produced immediately as the clapper hits the bell. Marked by rapidly decaying high intensity partials. Dominates the timbre of bells rung in rapid sequence. See tail.
Stretch
See octave stretch.
Strike note
The pitch assigned to a bell by the human ear. It does not correspond to any particular partial (though it is often close to an octave below the nominal). The strike effect is created by a psycho-acoustical phenomenon called the missing fundamental.
Superquint
One of the names given to the partial roughly a fifth above the nominal. Also known as the twelfth or the octave quint.
Tail
The slow decay of a bell's partials, often over tens of seconds. See splash.
Taylors
Taylors of Loughborough, one of the two main UK bellfounders. Was the first firm in the UK to introduce true-harmonic tuning.
Temperament
A way of tuning a diatonic scale to produce particular effects. See the entries for equal and meantone temperaments and just tuning.
Tierce
One of the five low partials of a bell, usually about a minor third above the prime. Often the loudest partial, it contributes to a bell's timbre but does not affect its pitch.
Timbre
The overall effect or quality of a bell's sound.
True harmonic
A system of bell tuning whereby the hum, prime and nominal partials are in octaves. The tierce is then usually a minor third and the quint roughly a fifth above the prime.
Tuning
The process of bringing the partials of a bell into harmonious arrangement (sometimes called inner tuning) and/or the strike notes of a peal of bells into harmonious arrangement (sometimes called outer tuning). Usually achieved by removing metal from the inside of the bell. (Just tuning is something different).
Virtual pitch
The creation by the ear of a pitch related to a set of partials in a harmonic series, but at a different frequency than any of them. The origin of the strike note and the secondary strike. See also spectral pitch.
Waist
The area of the bell between the crown and the soundbow.
Whitechapel
The Whitechapel Bellfoundry, one of the two main bellfounders in the UK. Previously traded as Mears and Stainbank, Lester and Pack, and various other names.

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Last updated May 17, 2002. Site created by Bill Hibbert, Great Bookham, Surrey