UK Registered Charity Number: 1154107
Conservation by Re-use
Helping churches acquire surplus and/or redundant bells to be hung for
English-style full-circle bell-ringing.
Sound of Bells – What is the Note of a bell?
There are three different ways the note of a bell can be shown - By Note, Strike Note or the frequency of the Nominal.
1) By NOTE
The simplest way is by the Note, for example 'Ab'. This notation is in common use, for example Doves' Guide and in many church ringing chambers. Unfortunately this information is usually incomplete as one needs to know which pitch and musical scale. Even if the scale and pitch are known, the bell could be up to half a semitone flat or sharp of the Note. This deficiency is overcome nowadays by specifying the difference between the International and actual pitch in cents : e.g. Ab+12 cents.
Unless specified otherwise, Notes given in bell-founders & hangers reports use the Standard International pitch.
2) By Strike Note
For a True Harmonic tuned (Simpson-tuned) bell the strike note will be half the frequency of the Nominal partial, and the same frequency as the Prime partial.
The frequencies are usually given in the SI units of Hertz (Hz) but the superseded terminology of Cycles per Second (c.p.s) is still used by some members of the trade.
A bell of Nominal frequency 798Hz could be described as having a Strike Note of 399Hz (c.p.s).
3) By Nominal Frequency
Frequencies are independent of musical scale and allow a quicker comparison between bells.
It is common for the frequencies of the Hum, Prime, Tierce and Quint partials to be given as well as the Nominal partial. This information may be accompanied by the difference (or error) between the bell's partial and the theoretical value of a True Harmonic tuned bell.
Error (in cents) = 1200 log fpartial
log(2) fnominal * Ratiopartial
fpartial is the frequency of the partial.
fnominal is the frequency of the Nominal.
Ratiopartial is the True Harmonic tuned ratio for the partial. The ratios for True Harmonic tuning are: Hum : 0.25, Prime : 0.50, Tierce : 0.60 and Quint : 0.75, Nominal : 1. More information about True Harmonic tuning.
For example a bell of Nominal frequency 800Hz and Hum frequency 215Hz would be 125 cents sharp of a True Harmonic tuned bell which should have a hum note of 200Hz.
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