Dissonance has been understood and heard differently in different musical traditions, cultures, styles, and time periods. Relaxation and tension have been used as analogy since the time of Aristotle till the present. The terms dissonance and consonance are often considered equivalent to tension and relaxation. A cadence is (among other things) a place where tension is resolved; hence the long tradition of thinking of a musical phrase as consisting of a
cadence and a passage of gradually accumulating tension leading up to it. Various psychological principles constructed through the audience's general conception of tonal fluidity determine how a listener will distinguish an instance of dissonance within a musical composition. Based on one's developed conception of the general tonal fusion within the piece, an unexpected tone played slightly variant to the overall schema will generate a psychological need for resolve. When the consonant is followed thereafter, the listener will encounter a sense of resolution. Within Western music, these particular instances and psychological effects within a composition have come to possess an ornate connotation. The application of consonance and dissonance "is sometimes regarded as a property of isolated
sonorities that is independent of what precedes or follows them. In most Western music, however, dissonances are held to
resolve onto following consonances, and the principle of
resolution is tacitly considered integral to consonance and dissonance".
Antiquity and the middle ages In Ancient Greece,
armonia denoted the production of a unified complex, particularly one expressible in numerical ratios. Applied to music, the concept concerned how sounds in a scale or a melody fit together (in this sense, it could also concern the tuning of a scale). The term
symphonos was used by Aristoxenus and others to describe the intervals of the fourth, the fifth, the octave and their doublings; other intervals were said
diaphonos. This terminology probably referred to the
Pythagorean tuning, where fourths, fifths and octaves (ratios 4:3, 3:2 and 2:1) were directly tunable, while the other scale degrees (other 3 prime ratios) could only be tuned by combinations of the preceding. Until the advent of
polyphony and even later, this remained the basis of the concept of consonance versus dissonance (
symphonia versus
diaphonia) in Western music theory. In the early Middle Ages, the Latin term translated either
armonia or
symphonia. Boethius (6th century) characterizes consonance by its sweetness, dissonance by its harshness: "Consonance () is the blending () of a high sound with a low one, sweetly and uniformly () arriving to the ears. Dissonance is the harsh and unhappy percussion () of two sounds mixed together ()". It remains unclear, however, whether this could refer to simultaneous sounds. The case becomes clear, however, with Hucbald of Saint Amand (), who writes: : "Consonance () is the measured and concordant blending () of two sounds, which will come about only when two simultaneous sounds from different sources combine into a single musical whole () ... There are six of these consonances, three simple and three composite, ... octave, fifth, fourth, and octave-plus-fifth, octave-plus-fourth and double octave". According to
Johannes de Garlandia: • Perfect consonance: unisons and octaves. :: ( :: "[Consonance] is said perfect, when two voices are joined at the same time, so that the one, by audition, cannot be distinguished from the other because of the concordance, and it is called equisonance, as in unison and octave.") • Median consonance: fourths and fifths. ::( :: "Consonances are said median, when two voices are joined at the same time, which neither can be said perfect, nor imperfect, but which partly agree with the perfect, and partly with the imperfect. And they are of two species, namely the fifth and the fourth.") • Imperfect consonance: minor and major thirds. (Imperfect consonances are not formally mentioned in the treatise, but the quotation above concerning median consonances does refer to imperfect consonances, and the section on consonances concludes: :: :: "So it appears that there are six species of consonances, that is: unison, octave, fifth, fourth, minor third, major third." The last two are implied to be "imperfect consonances" by deduction.) • Imperfect dissonance: major sixth (tone + fifth) and minor seventh (minor third + fifth). :: ( :: [Dissonances] are said imperfect, when two voices are joined so that by audition although they can to some extent match, nevertheless they do not concord. And there are two species, namely tone plus fifth and minor third plus fifth.") • Median dissonance: tone and minor sixth (
semitone + fifth). :: ( :: [Dissonances] are said median when two voices are joined so that they partly match the perfect, partly the imperfect. And they are of two species, namely tone and semitone plus fifth.") • Perfect dissonance: semitone, tritone, major seventh (major third + fifth). (Here again, the perfect dissonances can only be deduced by elimination from this phrase: :: :: These species of dissonances are seven: semitone, tritone, major third plus fifth; tone plus fifth, minor third plus fifth; tone and semitone plus fifth.") One example of imperfect consonances previously considered dissonances in
Guillaume de Machaut's "Je ne cuit pas qu'onques": According to Margo Schulter: Stable: • Purely blending: unisons and octaves • Optimally blending: fourths and fifths Unstable: • Relatively blending: minor and major thirds • Relatively tense: major seconds, minor sevenths, and major sixths • Strongly discordant: minor seconds, tritonus, and major sevenths, and often minor sixths "Perfect" and "imperfect" and the notion of being () must be taken in their contemporaneous
Latin meanings (
perfectum ,
imperfectum ) to understand these terms, such that imperfect is "unfinished" or "incomplete" and thus an imperfect dissonance is "not quite manifestly dissonant" and perfect consonance is "done almost to the point of excess". Also,
inversion of intervals (
major second in some sense equivalent to
minor seventh) and
octave reduction (
minor ninth in some sense equivalent to minor second) were yet unknown during the Middle Ages. Due to the different
tuning systems compared to
modern times, the minor seventh and
major ninth were "harmonic consonances", meaning that they correctly reproduced the interval ratios of the
harmonic series which softened a bad effect. They were also often filled in by pairs of perfect fourths and perfect fifths respectively, forming
resonant (blending) units characteristic of the musics of the time, where "resonance" forms a
complementary trine with the categories of consonance and dissonance. Conversely, the thirds and
sixths were
tempered severely from
pure ratios, and in practice usually treated as dissonances in the sense that they had to
resolve to form complete
perfect cadences and stable sonorities. The salient differences from modern conception: • parallel fourths and fifths were acceptable and necessary, open fourths and fifths inside octaves were the characteristic stable sonority in 3 or more voices, • minor sevenths and major ninths were fully structural, • tritones—as a deponent sort of fourth or fifth—were sometimes stacked with perfect fourths and fifths, • thirds and sixths (and tall
stacks thereof) were not the sort of intervals upon which stable harmonies were based, • final cadential consonances of fourth, fifths, and octaves need not be the target of "resolution" on a beat-to-beat (or similar) time basis: minor sevenths and major ninths may move to octaves forthwith, or sixths to fifths (or minor sevenths), but the fourths and fifths within might become "dissonant" 5:3, 6:3, or 6:4
chordioids, continuing the succession of non-consonant sonorities for timespans limited only by the next cadence.
Renaissance In
Renaissance music, the perfect fourth above the bass was considered a dissonance needing immediate resolution. The
regola delle terze e seste ("rule of thirds and sixths") required that imperfect consonances should resolve to a perfect one by a half-step progression in one voice and a whole-step progression in another. The viewpoint concerning successions of imperfect consonances—perhaps more concerned by a desire to avoid monotony than by their dissonant or consonant character—has been variable. Anonymous XIII (13th century) allowed two or three, Johannes de Garlandia's
Optima introductio (13th–14th century) three, four or more, and Anonymous XI (15th century) four or five successive imperfect consonances.
Adam von Fulda wrote "Although the ancients formerly would forbid all sequences of more than three or four imperfect consonances, we more modern do not prohibit them."
Common practice period 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: •
Major second and
minor seventh •
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" by some 20th-century composers. Early-20th-century American composer
Henry Cowell viewed
tone clusters as the use of higher and higher overtones. Composers in the Baroque era were well aware of the expressive potential of dissonance: in Bach's
Well-Tempered Clavier, vol. I (Preludio XXI) 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 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." '' closing bars In the opening aria of Cantata
BWV 54,
Widerstehe doch der Sünde ("do resist sin"), 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". Gillies Whittaker 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": The Benedictus from
Michael Haydn's Missa Quadragesimalis contains a passage of contrapuntal treatment consisting of various dissonances such as a
ninth chord without its fifth, an
augmented triad, a
half-diminished seventh chord, and a
minor seventh chord.
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 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 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 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 sound is further complicated with the addition of a
diminished seventh chord, creating, in Scruton's words "the most atrocious dissonance that Beethoven ever wrote, a
first inversion D-minor triad containing all the notes of the D
minor harmonic scale":
Robert Schumann's song "Auf einer Burg" from his cycle
Liederkreis, Op. 39, climaxes on a striking dissonance in the fourteenth bar. As
Nicholas Cook points out, this is "the only chord in the whole song that Schumann marks with an accent". Cook goes on to stress that what makes this chord so effective is Schumann's placing of it in its musical context: "in what leads up to it and what comes of it". Cook explains further how the interweaving of lines in both piano and voice parts in the bars leading up to this chord (bars 9–14) "are set on a kind of collision course; hence the feeling of tension rising steadily to a breaking point". ] Wagner made increasing use of dissonance for dramatic effect as his style developed, particularly in his later operas. In the scene known as "Hagen's Watch" from the first act of
Götterdämmerung, according to Scruton the music conveys a sense of "matchless brooding evil", and the excruciating dissonance in bars 9–10 below it constitute "a semitonal wail of desolation". ] Another example of a cumulative build-up of dissonance from the early 20th century (1910) can be found in the Adagio that opens
Gustav Mahler's unfinished
10th Symphony:
Richard Taruskin parsed this chord (in bars 206 and 208) as a "diminished nineteenth ... a searingly dissonant dominant harmony containing nine different pitches. Who knows what
Guido Adler, for whom the second and Third Symphonies already contained 'unprecedented cacophonies', might have called it?" One example of modernist dissonance comes from a work that received its first performance in 1913, three years after the
Mahler:
Neo-classic harmonic consonance theory constructed from notes of the Lydian mode
George Russell, in his 1953
Lydian Chromatic Concept of Tonal Organization, presents a slightly different view from classical practice, one widely taken up in
Jazz. He regards the tritone over the tonic as a rather consonant interval due to its derivation from the Lydian dominant thirteenth chord. In effect, he returns to a
Medieval consideration of "harmonic consonance": that intervals when not subject to
octave equivalence (at least not by contraction) and correctly reproducing the
mathematical ratios of the
harmonic series are truly non-dissonant. Thus the
septimal minor seventh,
major ninth,
neutral eleventh (
semiaugmented fourth),
neutral thirteenth, and
diminished fifteenth must necessarily be consonant. Most of these pitches exist only in a universe of
microtones smaller than a
halfstep; notice also that
we already freely take the
flat (minor) seventh note for the
just seventh of the
harmonic series in
chords. Russell extends by approximation the virtual merits of harmonic consonance to the
12TET tuning system of
Jazz and the 12-note octave of the
piano, granting consonance to the
sharp eleventh note (approximating the harmonic
eleventh), that accidental being the sole pitch difference between the
major scale and the
Lydian mode. (In another sense, that
Lydian scale representing the provenance of the
tonic chord (with major seventh and
sharp fourth) replaces or supplements the
Mixolydian scale of the
dominant chord (with minor seventh and
natural fourth) as the source from which to derive
extended tertian harmony.) Dan Haerle, in his 1980
The Jazz Language, extends the same idea of harmonic consonance and intact
octave displacement to alter
Paul Hindemith's
Series 2 gradation table from
The Craft of Musical Composition. In contradistinction to Hindemith, whose scale of consonance and dissonance is currently the
de facto standard, Haerle places the minor ninth as the most dissonant interval of all, more dissonant than the minor second to which it was once considered by all as octave-equivalent. He also promotes the tritone from most-dissonant position to one just a little less consonant than the perfect fourth and perfect fifth. For context: unstated in these theories is that musicians of the
Romantic Era had effectively promoted the major ninth and minor seventh to a legitimacy of harmonic consonance as well, in their fabrics of 4-note chords. ==See also==