page_title: Consonance and dissonance
section_title: Common practice period
hierarchical_section_title: Consonance and dissonance / In history of Western music / Common practice period
caption_attribution_description: English: Mozart's String Quartet No. 19, "Dissonance", opening bars
context_page_description: In music, consonance and dissonance are categorizations of simultaneous or successive sounds. Within the Western tradition, consonance is typically associated with sweetness, pleasantness, and acceptability; dissonance is associated with harshness, unpleasantness, or unacceptability although this depends also on familiarity and musical expertise. The terms form a structural dichotomy in which they define each other by mutual exclusion: a consonance is what is not dissonant, and a dissonance is what is not consonant. However, a finer consideration shows that the distinction forms a gradation, from the most consonant to the most dissonant. As Hindemith stressed, "The two concepts have never been completely explained, and for a thousand years the definitions have varied". The term sonance has been proposed to encompass or refer indistinctly to the terms consonance and dissonance.
context_section_description: In the common practice period, musical style required preparation for all dissonances, followed by a resolution to a consonance. There was also a distinction between melodic and harmonic dissonance. Dissonant melodic intervals included the tritone and all augmented and diminished intervals. Dissonant harmonic intervals included:
  Minor second and major seventh
  Augmented fourth and diminished fifth (enharmonically equivalent, tritone)
  Early in history, only intervals low in the overtone series were considered consonant. As time progressed, intervals ever higher on the overtone series were considered as such. The final result of this was the so-called "emancipation of the dissonance" (Schoenberg 1975, pp. 258–64) by some 20th-century composers. Early-20th-century American composer Henry Cowell viewed tone clusters as the use of higher and higher overtones (Cowell 1969, pp. 111–39).
  
  Composers in the Baroque era were well aware of the expressive potential of dissonance:
  
  Bach uses dissonance to communicate religious ideas in his sacred cantatas and Passion settings. At the end of the St Matthew Passion, where the agony of Christ’s betrayal and crucifixion is portrayed, John Eliot Gardiner (2013, 427) hears that "a final reminder of this comes in the unexpected and almost excruciating dissonance Bach inserts over the very last chord: the melody instruments insist on B natural—the jarring leading tone—before eventually melting in a C minor cadence." 
   In the opening aria of Cantata BWV 54, Widerstehe doch der Sünde ("upon sin oppose resistance"), nearly every strong beat carries a dissonance:
  Albert Schweitzer says that this aria “begins with an alarming chord of the seventh… It is meant to depict the horror of the curse upon sin that is threatened in the text" (Schweitzer 1905, 53). Gillies Whittaker (1959, 368) points out that “The thirty-two continuo quavers of the initial four bars support four consonances only, all the rest are dissonances, twelve of them being chords containing five different notes. It is a remarkable picture of desperate and unflinching resistance to the Christian to the fell powers of evil.”
  
  According to H.C. Robbins Landon, the opening movement of Haydn’s Symphony No. 82, "a brilliant C major work in the best tradition" contains "dissonances of barbaric strength that are succeeded by delicate passages of Mozartean grace." (Landon 1955, p. 415):
  Mozart's music contains a number of quite radical experiments in dissonance.  The following comes from his Adagio and Fugue in C Minor, K. 546:
  
  Mozart’s Quartet in C major, K465 opens with an adagio introduction that gave the work its nickname, the “Dissonance Quartet”:
  There are several passing dissonances in this adagio passage, for example on the first beat of bar 3.  However the most striking effect here is implied, rather than sounded explicitly.  The A flat in the first bar is contradicted by the high A natural in the second bar, but these notes do not sound together as a discord. (See also False relation.)
  
  An even more famous example from Mozart comes in a magical passage from the slow movement of his popular "Elvira Madigan" Piano Concerto 21, K467, where the subtle, but quite explicit dissonances on the first beats of each bar are enhanced by exquisite orchestration:
  Philip Radcliffe (1978, 52) speaks of this as “a remarkably poignant passage with surprisingly sharp dissonances." Radcliffe says that the dissonances here "have a vivid foretaste of Schumann and the way they gently melt into the major key is equally prophetic of Schubert." Eric Blom (1935, p. 226) says that this movement must have "made Mozart's hearers sit up by its daring modernities... There is a suppressed feeling of discomfort about it." 
  
  The finale of Beethoven’s Symphony No. 9 opens with a startling discord, consisting of a B flat inserted into a D minor chord:
  Roger Scruton (2009, 101) alludes to Wagner’s description of this chord as introducing “a huge Schreckensfanfare—horror fanfare.” When this passage returns later in the same movement (just before the voices enter) the so
caption: Mozart Dissonance Quartet opening bars.
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