There are various ways that church bells can be used, and this can affect the way they are tuned. The three ways considered in this section of the paper are:
- sounding singly
- playing as part of a carillon
- ringing in changes English style.
The last is of most interest, but the first two are briefly discussed to set the scene for certain conclusions about use for change ringing.
Bells rung singly
When bells are rung singly, unlike the case for use in a carillon or part of a change-ringing peal, they need not be in tune with anything else, but can be judged alone on their merits. There are two different aesthetics of single bells; either all low partials are exactly in tune with one another, and the bell is clappered in such a way that higher or out of tune partials are subdued. Then, the effect is of sweetness and sonority. Alternatively, for heavier bells only, an effect of mass or percussive grandeur can be effective. For this, true-harmonic tuning may not be necessary (or even possible, for very heavy bells that cannot be mounted on the tuning machine).
A good example of this latter class is Big Ben, for which the English have great affection despite its old style tuning and a crack! There is something dramatic and appealing about the sound of a huge mass of metal despite a certain lack of tunefulness. For another example, here is the largest bell of Rostov cathedral in Russia. Its nominal is 252Hz, and its weight is given as about 32 tons . . .
Bells in a carillon
The next case is that of bells used in a carillon. Here, completely different rules apply. First, the strike notes of all the bells in the carillon must be exactly in tune. Secondly, several bells will be sounded in rapid sequence or together. This means that all the partials of the bells must be related in some way if discords are not to occur. Unfortunately there is no way to tune bells to make this true for all combinations and in all keys. For example, the table below shows the lowest five partials of three bells rung together, sounding C, E and G (the major triad). Sub- and superscripts show the octaves.
|Partial||Bell 1||Bell 2||Bell 3|
As can be seen, even without the higher partials that will inevitably be present, we have Eflat sounding against E and Bflat against B in this supposedly harmonious chord.
Three things are done to reduce this effect and make carillon music tolerable to the ear:
- music is often arranged with runs and arpeggios rather than block chords to try to avoid bells with clashing partials sounding simultaneously
- true-harmonic tuning is used to ensure that partials in different bells with the same pitch do not clash
- the profile and clappering of the bells is arranged to minimise the higher partials.
The use of runs and arpeggios in carillon music means that, as with change ringing, the sound of a bell in the first few hundred milliseconds is important to perceptions of quality.
Bells in changes
The final case, and one that proves to be of great interest, is that of change ringing. The chief characteristic of this way of using bells is that bells never strike simultaneously, but at strict time intervals apart. They are rung sufficiently quickly that the long-lived partials of all the bells sound together. As each bell sounds, its strike note assumes temporary prominence before merging back into the mass.
To give some idea of the time intervals involved, let’s take two cases: a ring of 5 bells and a ring of 12. On 5 bells, a peal of 5000 changes takes about two hours and forty-five minutes – which is 9,900s. Assuming an open handstroke of one blow, this means that the time interval between each bell striking is about 360ms. On 12 bells, a peal takes about three and a half hours – which is 12,600s. Assuming an open handstroke of half a blow, this means that the time interval between each bell striking is about 200ms.
Here is an example of twelve bells being rung in rounds. (With thanks to Chris Caton and the ringers of St Mary, Redcliffe, Bristol.)
A similar exercise to that done for the carillon chord but for the larger numbers of bells will show that the sound of all the partials of the peal sounding together is necessarily discordant. Therefore, provided that all the strike notes of the bells are in tune, the sound each bell produces in the first 200 – 300ms is key to the quality of the peal.
Experience has shown that, for change ringing bells, the quality or timbre of the bells is as important as their pitch. Unlike the case for the carillon, quite wide tolerances in the pitch of change ringing bells can be accommodated.