Re: [LAU] Bell characteristics (list of partials)

On Sun, Dec 11, 2011 at 10:52:31PM +0100, Julien Claassen wrote:

> This sounds valuable. My first experiments - mainly trial and error,
> based on basic theory - weren't good at all. :-(

Depends on what you consider 'basic theory'. The simple fact is
that the partials of a bell sound are _not_ a simple harmonic
series. In its most basic form, a bell sound will consist of
five partials:

1. Nominal - this is the nominal frequency of the bell.
2. Prime - one octave below the nominal.
3. Hum - two octaves below the nominal.
4. Tierce - a minor (sometimes major) third above the prime.
5. Quint - a fifth above the prime.

There will be higher components as well in many cases, in
particular higher thirds and fifths, but these are never
exact harmonics of the lower ones.

This is a much simplified model. In most cases the two
octaves are not exact (the 'hum' is usually higher) and
this does not necessarily mean a bad sound. Same for the
smaller intervals.

The reason why inexact intervals are perfectly possible
and do not produce an ugly sound is that none of these
partials have significant higher harmomics - they are
pure sine frequencies. So there is no beating of higher
harmonics, which is what makes most detuned instruments
sound bad.

Except for the 'hum', these components will usually
have a normal exponential decay (roughly). The 'hum'
is different: it starts at low amplitude, and rises
during a second or two before decaying.

Ciao,

-- 
FA
Vor uns liegt ein weites Tal, die Sonne scheint - ein Glitzerstrahl.
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