page_title: Bell
section_title: Bell tuning
hierarchical_section_title: Bell / Bellfounding / Bell tuning
caption_attribution_description: English: Spectrum of the tenor bell at Winchester Cathedral as analyzed using FFT by Jonathan Harvey for his piece Mortuos Plango, Vivos Voco. Note that the major third in the second octave (F rather than E&#x266e;) is closer to the perfect fourth as is supposedly common in more modern bells. Sources Roads, Curtis, ed. (1992). Harvey Jonathan. "Mortuos Plango, Vivos Voco: A Realization at IRCAM", The Music Machine, p.92. ISBN&#160;9780262680783. Harvey added, "a clearly audible, slow-decaying partial at 347 Hz with a beating component in it. It is a resultant of the various F harmonic series partials that can be clearly seen in the spectrum (5, [6], 7, 9, 11, 13, 17, etc.) beside the C-related partials." Downes, Michael (2009). Jonathan Harvey: Song offerings and White as jasmine, p.22. ISBN&#160;9780754660224.
context_page_description: A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an internal "clapper" or "uvula", an external hammer, or—in small bells—by a small loose sphere enclosed within the body of the bell.
  Bells are usually cast from bell metal for its resonant properties, but can also be made from other hard materials; this depends on the function. Some small bells such as ornamental bells or cowbells can be made from cast or pressed metal, glass or ceramic, but large bells such as a church, clock and tower bells are normally cast from bell metal.
  Bells intended to be heard over a wide area can range from a single bell hung in a turret or bell-gable, to a musical ensemble such as an English ring of bells, a carillon or a Russian zvon which are tuned to a common scale and installed in a bell tower. Many public or institutional buildings house bells, most commonly as clock bells to sound the hours and quarters.
context_section_description: Large bells are generally around 80% copper and 20% tin (bell metal), which has been found empirically to give the most pleasant tone. However, the tone of a bell is mostly due to its shape. A bell is regarded as having a good tone when it's "in tune with itself". In western bell founding, this is known as "harmonic tuning" of a bell, which results in the bell's strongest harmonics being in harmony with each other and the strike note. This produces the brightest and purest sound, which is the attractive sound of a good bell. A huge amount of effort has been expended over the centuries in finding the shape which will produce the harmonically tuned bell.
  The accompanying musical staves show the series of harmonics which are generated when a bell is struck. The Erfurt bell is notable that it although it is an old bell, it is harmonically tuned, but was not typical of its time. Pieter and François Hemony in the 17th century reliably cast many bells for carillons of unequalled quality of tuning for the time, but after their death, their guarded trade secrets were lost, and not until the 19th century were bells of comparable tuning quality cast. It was only in modern times that repeatable harmonic tuning using a known scientific basis was achieved. The main partials (or harmonics) of a well-tuned bell are:
  hum note (an octave below the named note)
  strike tone (also called tap note or named note)
  tierce (a minor third above named note)
  quint (a fifth above named note)
  nominal (an octave above named note)
  Further, less-audible,  harmonics include the major third and a perfect fifth in the second octave above the named note.
  This quest by various founders over centuries of bell founding has resulted in the development of an optimum profile for casting each size of a bell to give true harmonic tuning. Although bells are cast to accurate patterns, variations in casting mean that a final tuning is necessary as the shape of the bell is critical in producing the desired strike note and associated harmonics. Tuning is undertaken by clamping the bell on a large rotating table and using a cutting tool to remove metal. This is an iterative process in which metal is removed from certain parts of the bell to change certain harmonics. This process was made possible historically by the use of tuning forks to find sympathetic resonance on specific parts of a bell for the harmonic being tuned, but today electronic strobe tuners are normally used. To tune the strike note, the nominal or the strike note are tuned; the effect is usually the same because the nominal is one of the main partials that determines the tone of the strike note.  The thickness of a church bell at its thickest part, called the "sound bow", is usually one thirteenth its diameter. If the bell is mounted as cast, it is called a "maiden bell".
caption: Spectrum of the tenor bell of Winchester Cathedral as analyzed by Jonathan Harvey using FFT[21] "The bell produces a secondary pitch (f') which lies outside that 'inharmonic series though it is clearly audible when the bell is struck, 'to curiously thrilling and disturbing effect.'"[22] About this soundPlay approximation (help·info) The strike tone is middle C, the hum tone an octave below.
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