Dissonance refers to a combination of musical notes that are perceived as unstable, clashing, or creating tension. In traditional Western music, dissonant intervals and chords are often expected to resolve to consonant (stable and pleasing) ones. The degree of dissonance can vary, and its use is crucial for creating musical interest, drama, and emotional expression.
Common dissonant intervals include the major and minor second, the tritone (augmented fourth/diminished fifth), and various sevenths and ninths. Composers use dissonance to build anticipation, express conflict, or create a sense of unease. For instance, the opening chord of Igor Stravinsky's "The Rite of Spring" is famously dissonant, shocking audiences at its premiere.
The perception and use of dissonance have evolved significantly throughout music history. In the Medieval and Renaissance periods, strict rules governed its treatment. The Baroque and Classical eras saw a more systematic use of dissonance for expressive purposes, always within a framework of eventual resolution. The Romantic period pushed these boundaries further, and the 20th century saw composers like Stravinsky and Schoenberg embrace dissonance as a primary expressive tool.
Listen to the opening of Igor Stravinsky's "The Rite of Spring." Pay attention to the harsh, clashing harmonies, particularly in the "Augurs of Spring" section. Notice how the music creates a sense of raw power and primal energy through its bold and persistent use of dissonance, rather than seeking immediate resolution.