Bells may not be symmetrical about their vertical axis. This gives rise to the phenomenon of doublets. A doublet is a mode of vibration which sounds at two (usually closely spaced) frequencies rather than one. The easiest demonstration of this uses only a mug and a teaspoon. A mug is not symmetrical – it has […]
Bells are musical instruments, and are assigned a note on a musical scale which identifies them, and which is used to judge whether a bell is ‘in tune’ with others in a peal or chime. When asked what (single) note a church bell is sounding, most people pick a note about an octave below the […]
Many references describe the way bells are tuned; the Dave Kelly articles, George Elphick’s book ‘The Craft of The Bell Founder’, and Lehr’s paper. A quick recap will be useful. The theoretical background is given in the set of papers Rossing’s Acoustics of Bells. A vibrating bell produces many frequencies of sound, each produced by a different vibrational mode […]
This series of articles was written 20 years ago, before I started my PhD research. I have done minor updates to correct mistakes and mis-understandings on my part. These papers touch on issues that are explored in much more detail in my thesis. If you are looking for an introduction to bell acoustics with less […]
How bells make their sound is a complex but interesting subject. The discussion here is restricted to bells of typical ‘western’ profile, rather than those of the east which have a very different shape. Western bells are usually hit by an iron clapper at a point on the inside, near the bottom, or by an […]
The basic principle of frequency calibration is simple. If a reference tone of known frequency is available, it can be recorded along with the bell sound. When the bell sound is later analysed, the frequency of the reference tone is checked at the same time. If there is a discrepancy, work out the ratio of […]
The pages linked below give practical tips on recording bells for the purposes of tonal analysis (including taking recordings from Youtube, and how to do the tonal analysis with Wavanal. The detail given in previous version of these pages (written almost 20 years ago) on recording formats and recording devices has been completely re-written and […]
This page was originally written in October 2002, and has been substantially updated to only cover recording bells for tonal analysis, not recordings for general purposes. Also, audio technology has moved a long way since 2002! Andrew Wilby suggested I wrote the original paper. It included extracts from messages originally published on the Bell Historian’s chat […]
Bell weights, diameters and frequencies are obviously related; heavier bells sound a deeper note, and heavier bells are generally bigger in diameter. But are there any quantitative rules that allow, say, a bell’s weight to be estimated from its diameter and partial frequencies? Partial tones and bell diameters are generally easy to measure or are […]
The full reference for this paper is: Perrin R., Charnley T., DePont J., “Normal Modes of the Modern EnglishChurch Bell”, Journal of Sound and Vibration 90(1), pp29-49 (1983) It is reprinted in Rossing’s ‘Acoustics of Bells’. The work is certainly the most comprehensive investigation into the modes of vibration of a bell. Over a period […]