Dissonance

Dissonance: Dissonance is a sounding together of two or more notes perceived as having “roughness” or “tonal tension” according to the Grove Music Online. Dissonance can also be defined as those intervals that are generally considered “secondary and unstable” (The Harvard Dictionary of Music 4th ed., 209). Those that are excluded from the dissonance category are referred to as consonant. For example, suspensions are usually dissonant notes that resolve to form a more consonant interval, such as 7-6 suspensions. Perhaps the most applicable display of dissonance for all of us maybe that of the dissonance game.
As time has evolved, so has the acceptance, and therefore the classification, of dissonant intervals. The Babylonians considered everything to be dissonant other than the octave, fifth, octave-plus-fifth, fourth, and the double octave. By 1400, the list of dissonant intervals included seconds, fourths, sevenths, augmented/diminished intervals, and their compounds. Only 300 years later, theorist Schoenberg rejected any absolute distinction between consonance and dissonance.
The use of triads created the need to classify these chords also within the context of dissonance and consonance. Theorists concluded that diminished triads in root position and major, minor, and diminished triads in second inversion are dissonant.
For thousands of years, theorists have attempted to master the “correct” categorization of dissonance and consonance. Pythagoras believed that dissonances were made by the ratios of the string lengths. Others believe that it is defined by the properties of the overtone series and yet others believe it should simply be left for the audience to decide (209-210). To me, it obvious that society’s reaction to dissonance is constantly changing (Ravel and Debussy were the norm at one time and now Eminem rules…and that is just 100 years ago) and that no equation or “general feeling” regarding music that will ever completely catagorize it.