Consonance and dissonance: Encyclopedia II - Consonance and dissonance - Consonance

Consonance and dissonance - Consonance

Consonance has been defined variously through:

• Frequency ratios: with ratios of lower simple numbers being more consonant than those which are higher (Pythagoras). Many of these definitions do not require exact integer tunings, only approximation.
  • Coincidence of harmonics: with consonance being a greater coincidence of harmonics or partials (collectively overtones) (Helmholtz, 1877/1954). By this definition consonance is dependent not only on the quality of the interval between two notes, but the partials and thus sound quality (timbre) of those notes themselves.
  • Fusion or pattern matching: fundamentals may be perceived through pattern-matching of the separately analyzed partials to a best-fit exact-harmonic template (Gerson & Goldstein, 1978) or the best-fit subharmonic (Terhardt, 1974). Or harmonics may be perceptually fused into one entity, with consonances being those intervals which are more likely to be mistaken for unisons, the perfect intervals, because of the multiple estimates of fundamentals, at perfect intervals, for one harmonic tone (Terhardt, 1974). By these definitions inharmonic partials of otherwise harmonic spectra are usually processed separately (Hartmann et al., 1990), unless frequency or amplitude modulated coherently with the harmonic partials (McAdams, 1983). For some of these definitions neural-firing supplies the data for pattern-matching, see directly below (e.g., Moore, 1989; pp.183-187; Srulovicz & Goldstein, 1983).
  • Period length or neural-firing coincidence: with the length of periodic neural-firing created by two or more wave-forms, lower simple numbers creating shorter or common periods or higher coincidence of neural-firing and thus consonance (Patternson, 1986; Boomsliter & Creel, 1961; Meyer, 1898; Roederer, 1973, p.145-149). Pure tones cause neural-firing exactly with the period or some multiple of the pure tone.
• Critical band: Consonances are pitches farther apart than their critical bands.

In what is now called the common practice period consonant intervals include:

• Perfect consonances:
  • unisons and octaves
  • perfect fourths and perfect fifths
• Imperfect consonances:
  • major thirds and minor sixths
  • minor thirds and major sixths

This is as would be taught in a beginning music theory class, but intervals such as the thirds and sixths were once considered forbidden dissonances. Consonances may be used freely and unprepared, occurring on weak or strong beats.

Polyphonic cadences, requiring at least two voices, were created by successive dyads, the first an imperfect consonance on a weak beat, the second a perfect consonance on a strong beat, such as a major sixth moving to an octave (for instance, the major (imperfect) sixth D-B followed by the perfect octave C-C').

Consonance and dissonance - Source

• Burns, Edward M. (1999). "Intervals, Scales, and Tuning", The Psychology of Music second edition. Deutsch, Diana, ed. San Diego: Academic Press. ISBN 0122135644.

Adapted from the Wikipedia article "Consonance", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki