[LAU] Bell characteristics (list of partials)

[Folderol]

On Sun, 11 Dec 2011 22:19:13 +0000
Fons Adriaensen <fons at linuxaudio.org> wrote:

> 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,

Absolutely fascinating!
I always knew that bells were 'strange' but I never realised just *how*
strange! 

-- 
Will J Godfrey
http://www.musically.me.uk
Say you have a poem and I have a tune.
Exchange them and we can both have a poem, a tune, and a song.