From: JEMebius on
Androcles wrote:
> "Jay Bala" <jay1bala(a)gmail.com> wrote in message
> news:2abb25ee-7925-4d66-a5e4-62dce7d8293d(a)d37g2000yqm.googlegroups.com...
> | Who can give me a mathematical definition for consonant, possibly tied
> | to even order harmonics. I don't words, I want an equation.
> |
> | I have something, but I think its not the best. I wanted to see whats
> | out there before I put anymore time into it.
> |
> | Thanks,
> | Jay Bala.
> |
> http://www.merriam-webster.com/dictionary/consonant
> 1 : being in agreement or harmony : free from elements making for discord
> 2 : marked by musical consonances
> 3 : having similar sounds <consonant words>
> 4 : relating to or exhibiting consonance : resonant
>
>
> consonant = integer ratio
>
> Where a = x/y and a belongs to the set of natural numbers {1,2,3,...}, x and
> y are consonant.
>
> In music, F# = 1480 Hz and G = 1568 Hz are dissonant (and sound it),
> 1480/1568 = 0.943877551
> which is not an integer.
> However, for F# = 185 Hz and G = 18,130 Hz (185*98) can be mathematically
> consonant if G is taken from a different and much higher octave; but 18,130
> Hz
> is a higher frequency than most people can hear and we don't have 98 * 12 =
> 1176
> keys on a piano, most have only 88 keys or less.
> Therefore we can in practice limit the set of consonant natural numbers
> to those we can hear which have the ratio x/y that belong to the set
> {1,2,3,4,5,6,7} in music, but not in mathematics. There is no limitation
> to even or odd numbers being consonant in music or mathematics.
>
>

Google "measure of consonance" yields about 285 hits, among which...

http://www.huygens-fokker.org/bpsite/consonance.html
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.111.2789&rep=rep1&type=pdf

The latter paper mentions Leonhard Euler's Gradus function.

Another paper on measures of consonance:
http://staff.science.uva.nl/~ahoningh/publicaties/measures_of_consonance.pdf

This paper mentions Euler's treatise on music:
Euler, L. (1739). Tentamen novae theoriae musicae. (*)
In E. Bernoulli et al. (Ed.), Opera Omnia, Volume 1 of III,
Stuttgart. Teubner (1926).

This treatise presumably contains mathematical definitions of "consonant", "dissonant" and
"measure of consonance".

Happy tuning - happy singing: Johan E. Mebius

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(*) Essay on a new theory of music.