Bell Harmonic Partials: Difference between revisions
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Smaller bells will often only exhibit two to four partials that need tuning, simplifying the process to the point that an automated lathe equipped with a microphone and DSP analysis software can be employed during manufacture to reduce cost. | Smaller bells will often only exhibit two to four partials that need tuning, simplifying the process to the point that an automated lathe equipped with a microphone and DSP analysis software can be employed during manufacture to reduce cost. | ||
== | == The Strike Tone == | ||
This harmonic gives us the perceived pitch of the bell at the time it is struck. | |||
The strike tone is not directly measurable but is definitely perceptible. Generally it can be found by setting an oscillator to match the perceived note of the bell. Multiply the oscillator's frequency by two and you will generally find that the result matches the measured frequency of the Nominal partial. We have tested this theory even on really bad sounding bells. It somehow always works. | The strike tone is not directly measurable but is definitely perceptible as a subjective harmonic. Generally it can be found by setting an oscillator by ear to match the perceived note of the bell. Multiply the oscillator's frequency by two and you will generally find that the result matches the measured frequency of the Nominal partial. We have tested this theory even on really bad sounding bells. It somehow always works. | ||
When the ear-brain hears combinations of high tones, we think we hear a single lower tone. For instance a combination of a Nominal with an octave-Quint sounds like a single tone lower than them both. This may explain why Big Ben sounds to most listeners like an A even though it was cast to be an E. | When the ear-brain hears combinations of high tones, we think we hear a single lower tone. For instance a combination of a Nominal with an octave-Quint sounds like a single tone lower than them both. This may explain why Big Ben sounds to most listeners like an A even though it was cast to be an E. This effect may lead some seniors, with a limited range of hearing, to say that cast bronze bells sound out of tune to them. | ||
== | == References == | ||
Andre Lehr - The Art of the Carillon in the Low Countries | Andre Lehr - The Art of the Carillon in the Low Countries | ||
Andre Lehr - [http://www.hibberts.co.uk/lehr.htm Contemporary Dutch Bell-Founding Art] (English trans R. Selman and T. Marton) | |||
John Glanville and William M. Wolmuth - Clockmaking in England and Wales in the Twentieth Century: The Industrialized Manufacture of Domestic Mechanical Clocks | John Glanville and William M. Wolmuth - Clockmaking in England and Wales in the Twentieth Century: The Industrialized Manufacture of Domestic Mechanical Clocks | ||