Seventh chord: Difference between revisions
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In its earliest usage, the seventh was introduced solely as an [[nonchord tone|embellishing or nonchord tone]]. The seventh destabilized the triad, and allowed the composer to emphasize movement in a given direction. As time passed and the collective ear of the western world became more accustomed to [[Consonance and dissonance|dissonance]], the seventh was allowed to become a part of the chord itself, and in some modern music, jazz in particular, nearly every chord is a seventh chord. Additionally, the general acceptance of [[equal temperament]] during the 19th century reduced the dissonance of some earlier forms of sevenths. |
In its earliest usage, the seventh was introduced solely as an [[nonchord tone|embellishing or nonchord tone]]. The seventh destabilized the triad, and allowed the composer to emphasize movement in a given direction. As time passed and the collective ear of the western world became more accustomed to [[Consonance and dissonance|dissonance]], the seventh was allowed to become a part of the chord itself, and in some modern music, jazz in particular, nearly every chord is a seventh chord. Additionally, the general acceptance of [[equal temperament]] during the 19th century reduced the dissonance of some earlier forms of sevenths. |
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[[Image:Seventh chords frequency.png|thumb|center|400px|"A ranking by frequency of the seventh chords in major would be approximately that shown."<ref>Kostka |
[[Image:Seventh chords frequency.png|thumb|center|400px|"A ranking by frequency of the seventh chords in major would be approximately that shown."<ref>{{cite book|last1=Kostka|last2=Payne|date=1995|title=Tonal Harmony|page=225|edition=3rd|ISBN=0-07-300056-6}}</ref> |
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<br/>{{audio|Dominant seventh chord V7 in C.mid|Play V<sup>7</sup>}} ([[#Dominant seventh chord|Dominant]]), {{audio|Minor seventh chord on d ii7 in C.mid|ii<sup>7</sup>}} ([[#Major and minor seventh chords|Minor]]), {{audio|Leading-tone seventh chord in C major.mid|vii{{music|halfdim}}<sup>7</sup>}} ([[#Half-diminished seventh chord|Half-diminished]]), {{audio|Major seventh chord on F.mid|IVM<sup>7</sup>}} ([[#Major and minor seventh chords|Major]]), {{audio|Minor seventh chord on a vi7 in C.mid|vi<sup>7</sup>}}, {{audio|Major seventh chord on C.mid|IM<sup>7</sup>}}, or {{audio|Minor seventh chord on e iii7 in C.mid|iii<sup>7</sup>}}.]] |
<br/>{{audio|Dominant seventh chord V7 in C.mid|Play V<sup>7</sup>}} ([[#Dominant seventh chord|Dominant]]), {{audio|Minor seventh chord on d ii7 in C.mid|ii<sup>7</sup>}} ([[#Major and minor seventh chords|Minor]]), {{audio|Leading-tone seventh chord in C major.mid|vii{{music|halfdim}}<sup>7</sup>}} ([[#Half-diminished seventh chord|Half-diminished]]), {{audio|Major seventh chord on F.mid|IVM<sup>7</sup>}} ([[#Major and minor seventh chords|Major]]), {{audio|Minor seventh chord on a vi7 in C.mid|vi<sup>7</sup>}}, {{audio|Major seventh chord on C.mid|IM<sup>7</sup>}}, or {{audio|Minor seventh chord on e iii7 in C.mid|iii<sup>7</sup>}}.]] |
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== Classification of seventh chords == |
== Classification of seventh chords == |
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Most textbooks name these chords ''formally'' by the type of triad and type of seventh; hence, a chord consisting of a major triad and a minor seventh above the root is referred to as a major/minor seventh chord. When the triad type and seventh type are identical (i.e. they are both major, minor, or diminished), the name is shortened. For instance, a ''major/major'' seventh is generally referred to as a '''major''' seventh. This rule is not valid for augmented chords: since the augmented/augmented chord is not commonly used, the abbreviation '''augmented''' is used for ''augmented/minor'', rather than ''augmented/augmented''. Additionally, '''half-diminished''' stands for ''diminished/minor'', and '''dominant''' stands for ''major/minor''. When the type is not specified at all, the triad is assumed to be major, and the seventh is understood as a minor seventh (e.g. a "C" chord is a "C major triad", and a " |
Most textbooks name these chords ''formally'' by the type of triad and type of seventh; hence, a chord consisting of a major triad and a minor seventh above the root is referred to as a major/minor seventh chord. When the triad type and seventh type are identical (i.e. they are both major, minor, or diminished), the name is shortened. For instance, a ''major/major'' seventh is generally referred to as a '''major''' seventh. This rule is not valid for augmented chords: since the augmented/augmented chord is not commonly used, the abbreviation '''augmented''' is used for ''augmented/minor'', rather than ''augmented/augmented''. Additionally, '''half-diminished''' stands for ''diminished/minor'', and '''dominant''' stands for ''major/minor''. When the type is not specified at all, the triad is assumed to be major, and the seventh is understood as a minor seventh (e.g. a "C" chord is a "C major triad", and a "C<sup>7</sup>" chord is a "[[Dominant seventh chord|C major/minor seventh chord]]", also known as a "C dominant seventh chord"). For symbols used for seventh chords, see also [[Popular music symbols#Seventh chords]]. |
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=== Tertian === |
=== Tertian === |
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The most common chords are [[tertian]], constructed using a sequence of [[major third]]s (spanning 4 [[semitone]]s) and/or [[minor third]]s (3 semitones). Since there are 3 third intervals in a seventh chord (4 notes) and each can be major or minor, there are 8 possible combinations, however, only seven of them are commonly found in western music. The ''[[augmented augmented seventh chord]]'', defined by a root, a major third, an augmented fifth, and an [[augmented seventh]] (i.e., a sequence of 3 major thirds), is a rarely used tertian seventh chord. The reason is that the augmented seventh interval is [[enharmonically equivalent]] to one entire [[octave]] (in [[equal temperament]], 3 major thirds = 12 semitones = 1 octave) and is hence perfectly [[consonance and dissonance|consonant]] with the chord root. The seven commonly used chords are: |
The most common chords are [[tertian]], constructed using a sequence of [[major third]]s (spanning 4 [[semitone]]s) and/or [[minor third]]s (3 semitones). Since there are 3 third intervals in a seventh chord (4 notes) and each can be major or minor, there are 8 possible combinations, however, only seven of them are commonly found in western music. The ''[[augmented augmented seventh chord]]'', defined by a root, a major third, an augmented fifth, and an [[augmented seventh]] (i.e., a sequence of 3 major thirds, such as C–E–G{{music|#}}–B{{music|#}}), is a rarely used tertian seventh chord. The reason is that the augmented seventh interval is [[enharmonically equivalent]] to one entire [[octave]] (in [[equal temperament]], 3 major thirds = 12 semitones = 1 octave) and is hence perfectly [[consonance and dissonance|consonant]] with the chord root. The seven commonly used chords are: |
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!Third!!Fifth!!Seventh !! 1st!!2nd!!3rd |
!Third!!Fifth!!Seventh !! 1st!!2nd!!3rd |
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|[[Major seventh chord|Major seventh]] || [[Image:CMA 7.png|thumb|110px|{{Audio|Major seventh chord on C.mid|play}}]] || Cmaj<sup>7</sup><br>CM<sup>7</sup><br>C{{music|major}} || [[major third|major]] || [[perfect fifth|perfect]] || [[major seventh|major]] || major || minor || major |
|[[Major seventh chord|Major seventh]] || [[Image:CMA 7.png|thumb|110px|{{Audio|Major seventh chord on C.mid|play}}]] || Cmaj<sup>7</sup><br>CM<sup>7</sup><br>C{{music|major}}<sup>7</sup><br>C{{music|major}} || [[major third|major]] || [[perfect fifth|perfect]] || [[major seventh|major]] || major || minor || major |
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|[[Minor seventh chord|Minor seventh]] || [[Image:Cmi 7.png|thumb|110px|{{Audio|Minor seventh chord on C.mid|play}}]] || Cmin<sup>7</sup><br>Cm<sup>7</sup><br> |
|[[Minor seventh chord|Minor seventh]] || [[Image:Cmi 7.png|thumb|110px|{{Audio|Minor seventh chord on C.mid|play}}]] || Cmin<sup>7</sup><br>Cm<sup>7</sup><br>C−<sup>7</sup> || [[minor third|minor]] || perfect || [[minor seventh|minor]] || minor || major || minor |
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|[[Dominant seventh chord|Dominant seventh]] || [[Image:C7.png|thumb|110px|{{Audio|Dominant seventh chord on C.mid|play}}]] || C<sup>7</sup> || major || perfect || minor || major || minor || minor |
|[[Dominant seventh chord|Dominant seventh]] || [[Image:C7.png|thumb|110px|{{Audio|Dominant seventh chord on C.mid|play}}]] || C<sup>7</sup> || major || perfect || minor || major || minor || minor |
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|[[Diminished seventh chord|Diminished seventh]] || [[Image:Cº7.png|thumb|110px|{{Audio|Diminished seventh chord on C.mid|play}}]] || C |
|[[Diminished seventh chord|Diminished seventh]] || [[Image:Cº7.png|thumb|110px|{{Audio|Diminished seventh chord on C.mid|play}}]] || C{{music|diminished}}<sup>7</sup><br>Cdim<sup>7</sup> || minor || [[diminished fifth|diminished]] || [[diminished seventh|diminished]] || minor || minor || minor |
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|[[Half-diminished seventh chord|Half-diminished seventh]] || [[Image:Cmi 7 (b5).png|thumb|110px|{{Audio|Half-diminished seventh chord on C.mid|play}}]] || Cm<sup>7 |
|[[Half-diminished seventh chord|Half-diminished seventh]] || [[Image:Cmi 7 (b5).png|thumb|110px|{{Audio|Half-diminished seventh chord on C.mid|play}}]] || Cm<sup>7({{music|b}}5)</sup><br>C−<sup>7{{music|b}}5</sup><br>C{{music|halfdim}} || minor || diminished || minor || minor || minor || major |
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|[[Minor major seventh chord|Minor major seventh]] || [[Image:Cmi maj7.png|thumb|110px|{{Audio|Minor major seventh chord on C.mid|play}}]] || Cm<sup>maj7</sup><br>Cm<sup>M7</sup><br>Cm<sup>{{music|major}}7</sup><br> |
|[[Minor major seventh chord|Minor major seventh]] || [[Image:Cmi maj7.png|thumb|110px|{{Audio|Minor major seventh chord on C.mid|play}}]] || Cm<sup>maj7</sup><br>Cm<sup>M7</sup><br>Cm<sup>{{music|major}}7</sup><br>C−<sup>{{music|major}}7</sup> || minor || perfect || major || minor || major || major |
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|[[Augmented major seventh chord|Augmented major seventh]] || [[Image:Caug 7.png|thumb|110px|{{Audio|Augmented major seventh chord on C.mid|play}}]] || Cmaj<sup>7 |
|[[Augmented major seventh chord|Augmented major seventh]] || [[Image:Caug 7.png|thumb|110px|{{Audio|Augmented major seventh chord on C.mid|play}}]] || Cmaj<sup>7{{music|sharp}}5</sup><br>C+<sup>M7</sup><br>C+<sup>{{music|major}}7</sup> || major || [[augmented fifth|augmented]] || major || major || major || minor |
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=== Non-tertian === |
=== Non-tertian === |
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Seventh chords can also be constructed using augmented or diminished thirds. These chords are not tertian and can be used in non-tertian harmony. There are many (mathematically |
Seventh chords can also be constructed using augmented or diminished thirds. These chords are not tertian and can be used in non-tertian harmony. There are many (mathematically, 64) chords that can be built, however, only few of them are used and are listed in the table below: |
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!Third!!Fifth!!Seventh !! 1st!!2nd!!3rd |
!Third!!Fifth!!Seventh !! 1st!!2nd!!3rd |
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|[[Augmented minor seventh chord|Augmented seventh<br>(formally ''augmented/minor seventh'')]] || [[Image:Augmented dominant seventh chord.png|thumb|170px|{{Audio|Augmented seventh chord on C.mid|play}}]] || |
|[[Augmented minor seventh chord|Augmented seventh<br>(formally ''augmented/minor seventh'')]] || [[Image:Augmented dominant seventh chord.png|thumb|170px|{{Audio|Augmented seventh chord on C.mid|play}}]] || aug<sup>7</sup><br>+<sup>7</sup> || major || augmented || minor || major || major || [[Diminished third|diminished]]<br>(equiv. [[major second]]) |
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|[[Diminished major seventh chord|Diminished major seventh]] || [[Image:Diminished major seventh chord on C.png|thumb|170px|{{Audio|Diminished major seventh chord on C.mid|play}}]] || |
|[[Diminished major seventh chord|Diminished major seventh]] || [[Image:Diminished major seventh chord on C.png|thumb|170px|{{Audio|Diminished major seventh chord on C.mid|play}}]] || m<sup>M7{{music|b}}5</sup><br>−{{music|major}}7{{music|b}}5 || minor || diminished || major || minor || minor || [[Augmented third|augmented]]<br>(equiv. [[perfect fourth]]) |
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|[[Dominant seventh flat five chord|Dominant seventh flat five]] || [[Image:Dominant seventh flat five chord on C.png|thumb|170px|{{Audio|Dominant seventh flat five chord on C.mid|play}}]] || 7{{music|b}}5 || major || diminished || minor || major || diminished || major |
|[[Dominant seventh flat five chord|Dominant seventh flat five]] || [[Image:Dominant seventh flat five chord on C.png|thumb|170px|{{Audio|Dominant seventh flat five chord on C.mid|play}}]] || <sup>7{{music|b}}5</sup> || major || diminished || minor || major || diminished || major |
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{{Main|Dominant seventh chord}} |
{{Main|Dominant seventh chord}} |
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A '''dominant seventh chord''', or '''major-minor seventh chord''' is a [[chord (music)|chord]] composed of a [[root (chord)|root]], [[major third]], [[perfect fifth]], and [[minor seventh]]. It can be also viewed as a [[Major chord|major triad]] with an additional [[minor seventh]]. It is denoted using [[popular music symbols]] by adding a superscript "7" after the letter designating the chord root.<ref>Benward |
A '''dominant seventh chord''', or '''major-minor seventh chord''' is a [[chord (music)|chord]] composed of a [[root (chord)|root]], [[major third]], [[perfect fifth]], and [[minor seventh]]. It can be also viewed as a [[Major chord|major triad]] with an additional [[minor seventh]]. It is denoted using [[popular music symbols]] by adding a superscript "7" after the letter designating the chord root.<ref name=benwardsaker>{{cite book|last1=Benward|last2=Saker|date=2003|title=Music: In Theory and Practice, Vol. I|edition=7th|ISBN=978-0-07-294262-0}}</ref>{{rp|77}} The dominant seventh is found almost as often as the [[dominant (music)|dominant triad]].<ref name=benwardsaker />{{rp|199}} The chord can be represented by the [[Pitch class#Integer notation|integer notation]] {0, 4, 7, 10}. |
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The dominant seventh is found almost as often as the [[dominant (music)|dominant triad]].<ref>Benward & Saker (2003), p.199.</ref> |
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The chord can be represented by the [[Pitch class#Integer notation|integer notation]] {0, 4, 7, 10}. |
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Of all the seventh chords, perhaps the most important is the dominant seventh. It was the first seventh chord to appear regularly in [[classical music]]. The name comes from the fact that the flat seventh occurs naturally in the chord built upon the [[Dominant (music)|dominant]] (i.e., the fifth [[Scale degree|degree]]) of a given major [[diatonic scale]]. |
Of all the seventh chords, perhaps the most important is the dominant seventh. It was the first seventh chord to appear regularly in [[classical music]]. The name comes from the fact that the flat seventh occurs naturally in the chord built upon the [[Dominant (music)|dominant]] (i.e., the fifth [[Scale degree|degree]]) of a given major [[diatonic scale]]. |
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Take for example the C major scale (C, D, E, F, G, A, B, C): |
Take for example the C major scale (C, D, E, F, G, A, B, C): |
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The harmonic seventh interval is a minor seventh tuned in the 7:4 [[Interval ratio|pitch ratio]], one of the possible "just ratios" defined for this interval in [[just intonation]] (slightly below the width of a minor seventh as tuned in [[equal temperament]]). With just intonation on all notes of the harmonic seventh chord, the ratio between the frequencies of the pitches in the chord is 4:5:6:7. For example, a justly intuned A harmonic seventh chord in root position starting at [[A440 (pitch standard)|A440]] consists of the pitches 440 Hz, 550 Hz, 660 Hz, and 770 Hz. |
The harmonic seventh interval is a minor seventh tuned in the 7:4 [[Interval ratio|pitch ratio]], one of the possible "just ratios" defined for this interval in [[just intonation]] (slightly below the width of a minor seventh as tuned in [[equal temperament]]). With just intonation on all notes of the harmonic seventh chord, the ratio between the frequencies of the pitches in the chord is 4:5:6:7. For example, a justly intuned A harmonic seventh chord in root position starting at [[A440 (pitch standard)|A440]] consists of the pitches 440 Hz, 550 Hz, 660 Hz, and 770 Hz. |
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Sometimes called a "blue note", the harmonic seventh is used by singers, through note bending on guitars, and on other instruments not restricted to equal temperament. An often heard example of the harmonic seventh chord is the last word of the modern addition to the song "Happy Birthday to You", with the lyrics, "and many more!" The harmony on the word "more" is typically sung as a harmonic seventh chord.<ref name="Mathieu pg. 126">Mathieu |
Sometimes called a "blue note", the harmonic seventh is used by singers, through note bending on guitars, and on other instruments not restricted to equal temperament. An often heard example of the harmonic seventh chord is the last word of the modern addition to the song "Happy Birthday to You", with the lyrics, "and many more!" The harmony on the word "more" is typically sung as a harmonic seventh chord.<ref name="Mathieu pg. 126">{{cite book|last=Mathieu|first=W. A.|title=Harmonic Experience|publisher=Inner Traditions International|location=Rochester, VT|date=1997|ISBN=0-89281-560-4|page=126}}</ref> |
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Frequent use of the harmonic seventh chord is one of the defining characteristics of [[blues]] and [[Barbershop music|barbershop harmony]]; barbershoppers refer to it as "the barbershop seventh". Since barbershop music tends to be sung in [[just intonation]], the barbershop seventh chord may be accurately termed a harmonic seventh chord. The harmonic seventh chord is also widely used in |
Frequent use of the harmonic seventh chord is one of the defining characteristics of [[blues]] and [[Barbershop music|barbershop harmony]]; barbershoppers refer to it as "the barbershop seventh". Since barbershop music tends to be sung in [[just intonation]], the barbershop seventh chord may be accurately termed a harmonic seventh chord. The harmonic seventh chord is also widely used in blues-flavored music. As guitars, pianos, and other equal-temperament instruments cannot play this chord, it is frequently approximated by a dominant seventh. As a result, it is often called a dominant seventh chord and written with the same symbols (such as the blues progression I<sup>7</sup>–V<sup>7</sup>–IV<sup>7</sup>). |
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=== Major and minor seventh chords === |
=== Major and minor seventh chords === |
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[[File:Minor seventh chord on d ii7 in C.png|thumb|Minor seventh chord on |
[[File:Minor seventh chord on d ii7 in C.png|thumb|Minor seventh chord on D, ii<sup>7</sup> in C.]] |
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[[File:Major seventh chord on F.png|thumb|left|Major seventh chord on F, IV<sup>7</sup> in C.]] |
[[File:Major seventh chord on F.png|thumb|left|Major seventh chord on F, IV<sup>7</sup> in C.]] |
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{{Main|Major seventh chord|Minor seventh chord}} |
{{Main|Major seventh chord|Minor seventh chord}} |
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While the dominant seventh chord is typically built on the fifth (or dominant) degree of a major scale, the minor seventh chord is built on the second, third, or sixth degree. A minor seventh chord contains the same notes as an [[Sixth chord|added sixth chord]]. For example, C–E{{music|♭}}–G–B{{music|♭}} can function as both a C minor seventh and an E |
While the dominant seventh chord is typically built on the fifth (or dominant) degree of a major scale, the minor seventh chord is built on the second, third, or sixth degree. A minor seventh chord contains the same notes as an [[Sixth chord|added sixth chord]]. For example, C–E{{music|♭}}–G–B{{music|♭}} can function as both a C minor seventh and an E{{music|flat}} added sixth (Id chord). |
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Major seventh chords are usually constructed on the first or fourth degree of a scale, (in C or G major: C–E–G–B). Due to the major seventh interval between the root and seventh (C–B, an inverted minor second), this chord can sometimes sound dissonant, depending on the voicing used. For example, [[Burt Bacharach|Bacharach]] and [[Hal David|David]]'s ''[[Raindrops Keep Fallin' on My Head]]'' opens with a major chord followed by a major seventh in the next measure. |
Major seventh chords are usually constructed on the first or fourth degree of a scale, (in C or G major: C–E–G–B). Due to the major seventh interval between the root and seventh (C–B, an inverted minor second), this chord can sometimes sound dissonant, depending on the voicing used. For example, [[Burt Bacharach|Bacharach]] and [[Hal David|David]]'s ''[[Raindrops Keep Fallin' on My Head]]'' opens with a major chord followed by a major seventh in the next measure. |
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=== Half-diminished seventh chord === |
=== Half-diminished seventh chord === |
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[[File:Leading-tone seventh chord in C major.png|thumb|Leading-tone seventh chord (vii{{music|halfdim}}<sup>7</sup>) in C major, |
[[File:Leading-tone seventh chord in C major.png|thumb|Leading-tone seventh chord (vii{{music|halfdim}}<sup>7</sup>) in C major, B{{music|halfdim}}<sup>7</sup>.]] |
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{{Main|Half-diminished seventh chord}} |
{{Main|Half-diminished seventh chord}} |
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A half-diminished seventh chord is a seventh chord built from the seventh degree of a major scale. It |
A half-diminished seventh chord is a seventh chord built from the seventh degree of a major scale. It is considered "half-diminished" because a fully diminished seventh has a double-flatted (diminished) seventh, making it [[enharmonic]]ally the same as a major sixth. The half-diminished seventh chord uses a minor seventh over the root of a diminished triad. |
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Example: (in the key of C major) |
Example: (in the key of C major) B–D–F–A. |
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=== Diminished seventh chord === |
=== Diminished seventh chord === |
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[[File:Diminished7thandMinor9thComparison.png|thumb|left|A comparison of the |
[[File:Diminished7thandMinor9thComparison.png|thumb|left|A comparison of the diminished seventh and dominant 7{{music|b}}9 chords]] |
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{{Main|Diminished seventh chord}} |
{{Main|Diminished seventh chord}} |
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A diminished |
A diminished seventh chord is made of three superimposed minor thirds (e.g., B–D–F–A{{music|flat}}), which is two tritones a minor third apart (e.g., B–F, D–A{{music|flat}}). The diminished seventh chord has been used by composers and musicians for a variety of reasons over time. Some reasons include: as a symbol of [[Sturm und Drang]]; [[modulation (music)|modulation]]; and for characterisation. The diminished seventh chord is seen more frequently in late classical and romantic period works but is also found in [[Baroque]] and [[Renaissance]] period works, though not as frequently. |
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All of the elements of the |
All of the elements of the diminished seventh chord can be found in the dominant seventh flat nine (7{{music|b}}9) chord as seen in a comparison of the two chords. |
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==Inversions== |
==Inversions== |
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[[File:Inversion of seventh chord.svg|thumb|300px|right|Inversions of seventh chord]] |
[[File:Inversion of seventh chord.svg|thumb|300px|right|Inversions of a dominant seventh chord]] |
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There are four different inversions. |
There are four different [[inversion (music)|inversions]] of a seventh chord. Following [[basso continuo]] notation, the inversions are as follows: |
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*{{sup|7}} — GBD<u>F</u> |
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Seventh chord inversions are as follows: |
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* |
*{{su|p=6|b=5}} — BD<u>FG</u> |
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* |
*{{su|p=4|b=3}} — D<u>FG</u>B |
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* |
*{{sup|2}} — F<u>G</u>BD |
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*<math>{}^2</math> — F<u>GB</u>D |
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==See also== |
==See also== |
Revision as of 21:41, 29 March 2017
This article needs additional citations for verification. (November 2012) |
A seventh chord is a chord consisting of a triad plus a note forming an interval of a seventh above the chord's root. When not otherwise specified, a "seventh chord" usually means a dominant seventh chord: a major triad together with a minor seventh. However, a variety of sevenths may be added to a variety of triads, resulting in many different types of seventh chords.
In its earliest usage, the seventh was introduced solely as an embellishing or nonchord tone. The seventh destabilized the triad, and allowed the composer to emphasize movement in a given direction. As time passed and the collective ear of the western world became more accustomed to dissonance, the seventh was allowed to become a part of the chord itself, and in some modern music, jazz in particular, nearly every chord is a seventh chord. Additionally, the general acceptance of equal temperament during the 19th century reduced the dissonance of some earlier forms of sevenths.
Classification of seventh chords
Most textbooks name these chords formally by the type of triad and type of seventh; hence, a chord consisting of a major triad and a minor seventh above the root is referred to as a major/minor seventh chord. When the triad type and seventh type are identical (i.e. they are both major, minor, or diminished), the name is shortened. For instance, a major/major seventh is generally referred to as a major seventh. This rule is not valid for augmented chords: since the augmented/augmented chord is not commonly used, the abbreviation augmented is used for augmented/minor, rather than augmented/augmented. Additionally, half-diminished stands for diminished/minor, and dominant stands for major/minor. When the type is not specified at all, the triad is assumed to be major, and the seventh is understood as a minor seventh (e.g. a "C" chord is a "C major triad", and a "C7" chord is a "C major/minor seventh chord", also known as a "C dominant seventh chord"). For symbols used for seventh chords, see also Popular music symbols#Seventh chords.
Tertian
The most common chords are tertian, constructed using a sequence of major thirds (spanning 4 semitones) and/or minor thirds (3 semitones). Since there are 3 third intervals in a seventh chord (4 notes) and each can be major or minor, there are 8 possible combinations, however, only seven of them are commonly found in western music. The augmented augmented seventh chord, defined by a root, a major third, an augmented fifth, and an augmented seventh (i.e., a sequence of 3 major thirds, such as C–E–G♯–B♯), is a rarely used tertian seventh chord. The reason is that the augmented seventh interval is enharmonically equivalent to one entire octave (in equal temperament, 3 major thirds = 12 semitones = 1 octave) and is hence perfectly consonant with the chord root. The seven commonly used chords are:
Common name | Chord on C | Common symbols on C |
Intervals from root | Quality of consecutive thirds | ||||
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Third | Fifth | Seventh | 1st | 2nd | 3rd | |||
Major seventh | Cmaj7 CM7 CΔ7 CΔ |
major | perfect | major | major | minor | major | |
Minor seventh | Cmin7 Cm7 C−7 |
minor | perfect | minor | minor | major | minor | |
Dominant seventh | C7 | major | perfect | minor | major | minor | minor | |
Diminished seventh | Co7 Cdim7 |
minor | diminished | diminished | minor | minor | minor | |
Half-diminished seventh | Cm7(♭5) C−7♭5 Cø |
minor | diminished | minor | minor | minor | major | |
Minor major seventh | Cmmaj7 CmM7 CmΔ7 C−Δ7 |
minor | perfect | major | minor | major | major | |
Augmented major seventh | Cmaj7♯5 C+M7 C+Δ7 |
major | augmented | major | major | major | minor |
Non-tertian
Seventh chords can also be constructed using augmented or diminished thirds. These chords are not tertian and can be used in non-tertian harmony. There are many (mathematically, 64) chords that can be built, however, only few of them are used and are listed in the table below:
Common name | Chord on C | Common symbols on C |
Intervals from root | Quality of consecutive thirds | ||||
---|---|---|---|---|---|---|---|---|
Third | Fifth | Seventh | 1st | 2nd | 3rd | |||
Augmented seventh (formally augmented/minor seventh) |
aug7 +7 |
major | augmented | minor | major | major | diminished (equiv. major second) | |
Diminished major seventh | mM7♭5 −Δ7♭5 |
minor | diminished | major | minor | minor | augmented (equiv. perfect fourth) | |
Dominant seventh flat five | 7♭5 | major | diminished | minor | major | diminished | major |
In tuning systems other than equal temperament there are further possible seventh chords. In just intonation, for example, there is the harmonic seventh.
Types of seventh chords
Dominant seventh chord
A dominant seventh chord, or major-minor seventh chord is a chord composed of a root, major third, perfect fifth, and minor seventh. It can be also viewed as a major triad with an additional minor seventh. It is denoted using popular music symbols by adding a superscript "7" after the letter designating the chord root.[2]: 77 The dominant seventh is found almost as often as the dominant triad.[2]: 199 The chord can be represented by the integer notation {0, 4, 7, 10}.
Of all the seventh chords, perhaps the most important is the dominant seventh. It was the first seventh chord to appear regularly in classical music. The name comes from the fact that the flat seventh occurs naturally in the chord built upon the dominant (i.e., the fifth degree) of a given major diatonic scale.
Take for example the C major scale (C, D, E, F, G, A, B, C):
The note G is the dominant degree of C major—its fifth note. When we arrange the notes of the C major scale in ascending pitch and use only these notes to build a seventh chord, and we start with G (not C), then the resulting chord contains the four notes G–B–D–F and is called G dominant seventh (G7). The note F is a minor seventh from G, and is also called the dominant seventh with respect to G. However, the 'dominant' seventh is used on notes other than the dominant, such as the subdominant.
Harmonic seventh chord
The harmonic seventh chord is a dominant seventh chord formed by a major triad plus an harmonic seventh interval.
The harmonic seventh interval is a minor seventh tuned in the 7:4 pitch ratio, one of the possible "just ratios" defined for this interval in just intonation (slightly below the width of a minor seventh as tuned in equal temperament). With just intonation on all notes of the harmonic seventh chord, the ratio between the frequencies of the pitches in the chord is 4:5:6:7. For example, a justly intuned A harmonic seventh chord in root position starting at A440 consists of the pitches 440 Hz, 550 Hz, 660 Hz, and 770 Hz.
Sometimes called a "blue note", the harmonic seventh is used by singers, through note bending on guitars, and on other instruments not restricted to equal temperament. An often heard example of the harmonic seventh chord is the last word of the modern addition to the song "Happy Birthday to You", with the lyrics, "and many more!" The harmony on the word "more" is typically sung as a harmonic seventh chord.[3]
Frequent use of the harmonic seventh chord is one of the defining characteristics of blues and barbershop harmony; barbershoppers refer to it as "the barbershop seventh". Since barbershop music tends to be sung in just intonation, the barbershop seventh chord may be accurately termed a harmonic seventh chord. The harmonic seventh chord is also widely used in blues-flavored music. As guitars, pianos, and other equal-temperament instruments cannot play this chord, it is frequently approximated by a dominant seventh. As a result, it is often called a dominant seventh chord and written with the same symbols (such as the blues progression I7–V7–IV7).
Major and minor seventh chords
While the dominant seventh chord is typically built on the fifth (or dominant) degree of a major scale, the minor seventh chord is built on the second, third, or sixth degree. A minor seventh chord contains the same notes as an added sixth chord. For example, C–E♭–G–B♭ can function as both a C minor seventh and an E♭ added sixth (Id chord).
Major seventh chords are usually constructed on the first or fourth degree of a scale, (in C or G major: C–E–G–B). Due to the major seventh interval between the root and seventh (C–B, an inverted minor second), this chord can sometimes sound dissonant, depending on the voicing used. For example, Bacharach and David's Raindrops Keep Fallin' on My Head opens with a major chord followed by a major seventh in the next measure.
The major seventh is sometimes notated as Δ7 (a delta chord) or just a Δ (which has the same meaning).
Half-diminished seventh chord
A half-diminished seventh chord is a seventh chord built from the seventh degree of a major scale. It is considered "half-diminished" because a fully diminished seventh has a double-flatted (diminished) seventh, making it enharmonically the same as a major sixth. The half-diminished seventh chord uses a minor seventh over the root of a diminished triad.
Example: (in the key of C major) B–D–F–A.
Diminished seventh chord
A diminished seventh chord is made of three superimposed minor thirds (e.g., B–D–F–A♭), which is two tritones a minor third apart (e.g., B–F, D–A♭). The diminished seventh chord has been used by composers and musicians for a variety of reasons over time. Some reasons include: as a symbol of Sturm und Drang; modulation; and for characterisation. The diminished seventh chord is seen more frequently in late classical and romantic period works but is also found in Baroque and Renaissance period works, though not as frequently.
All of the elements of the diminished seventh chord can be found in the dominant seventh flat nine (7♭9) chord as seen in a comparison of the two chords.
Inversions
There are four different inversions of a seventh chord. Following basso continuo notation, the inversions are as follows:
- 7 — GBDF
- 6
5 — BDFG - 4
3 — DFGB - 2 — FGBD
See also
- Dominant seventh flat five chord
- Diminished major seventh chord
- Diminished minor seventh chord
- Augmented major seventh chord
- Augmented minor seventh chord
References
- ^ Kostka; Payne (1995). Tonal Harmony (3rd ed.). p. 225. ISBN 0-07-300056-6.
- ^ a b Benward; Saker (2003). Music: In Theory and Practice, Vol. I (7th ed.). ISBN 978-0-07-294262-0.
- ^ Mathieu, W. A. (1997). Harmonic Experience. Rochester, VT: Inner Traditions International. p. 126. ISBN 0-89281-560-4.
External links
- Tim Smith's 7th chord identification and construction drills in Javascript
- fretjam Guitar Theory - 7th Chords on Guitar