Tristimulus (audio)

The concept of tristimulus originates in the world of colour, describing the way three primary colours can be mixed together to create a given colour. By analogy, the musical tristimulus measures the mixture of harmonics in a given sound, grouped into three sections. The first tristimulus measures the relative weight of the first harmonic; the second tristimulus measures the relative weight of the 2nd, 3rd, and 4th harmonics taken together; and the third tristimulus measures the relative weight of all the remaining harmonics.

:$$T1 = frac{a_1}{sum_{h=1}^{H}{a_h

:$$T2 = frac{a_2 + a_3 + a_4}{sum_{h=1}^{H}{a_h

:$$T3 = frac{sum_{h=5}^{H}{a_h{sum_{h=1}^{H}{a_h

References

* G. Peeters (2003) “ [http://www.ircam.fr/anasyn/peeters/ARTICLES/Peeters_2003_cuidadoaudiofeatures.pdf A large set of audio features for sound description (similarity and classification) in the CUIDADO project] ”
* HF Pollard, EV Jansson (1982) "A Tristimulus Method for the Specification of Musical Timbre". Acustica.