SongTrellis
Music and Musical Know-how For You

Author:  David Luebbert Posted:  12/20/00; 10:08:31 AM Msg#:  1146 (top msg in thread) Prev/Next:  1145/1147 Reads:  6229

Chords are specified by formula A chord consists of a collection of three or more notes that are played simultaneously. Two pieces of information specify a chord: the chord root and the chord type. The chord root specification is the name of one of the twelve pitches that can be found in one octave of the chromatic scale. The possible chord root names are: C, C# or Db, D, D# or Eb, E, F, F# or Gb, G, G# or Ab, A, A# or Bb, and B. If the root of a chord was C, this would mean that pitches of C in one or more of the octaves that a piano, guitar or orchestra is able to play should be played as part of the chord. The other pitches that must be played in a chord of a particular type are selected by a formula that is unique to that type of chord. The formula for the other chord pitches of a chord type specifies the harmonic intervals that must be formed when those pitches are sounded with the chord root. The formula for a major triad prescribes that such a three note chord should include the chord root, a pitch that is a major third interval above the root or which is any number of octaves above or below that pitch, and a pitch that is a perfect fifth above the root or which is any number of octaves above or below that pitch. If your major triad is built on a C root, this means that a C in any octave can be included in the chord and that at least one of those C must be sounded. All notes that are a major third above any of those C pitches are named E. Any E in any octave may be included in the chord and at least one of those E's must be included. All notes that are a perfect fifth above C are named G. Any G in any octave may be included in the chord and at least one of those G's must be included. As you can see, there is no particular chord that is THE C triad. When a C triad is specified in a score, any chord out of a class that includes thousands of particular chords can be selected to satisfy that specification. Speaking of C triads makes sense in music because each of the playable C triads shares a common feeling with all other possible C triads. If you play a melody above a chord that is specified by a particular chord root and type, you can change the octave of any pitch in the chord or add pitches that are one or more octaves above or below a pitch that is in the chord and not alter the emotional meaning of the melody notes. Let's listen to several different C triads. First listen to one where C, E, and G are all played in the 4th octave. Next, here's one where the C is played in the 3rd octave, the G is played in the 4th, and the E is played in the 5th. Here's one where an E is played in octave 3, and G and C are played in octave 4. Finally, here's a C chord that plays every C, E, and G in octaves 2, 3, 4 and 5. Let's repeat this exercise for the F7 chord. F7 chords are four note chords that include the root, the major third interval above the root, a perfect fifth above the root, and a minor seventh above the root. In this chord, any F in any octave may be played an at least one of those Fs must be played. Notes that are a major third above the F root would be named A, so any A pitch in any octave may be played in the chord and at least one of those As must me played. Notes that are a perfect fifth above the F root are named C, so any of the pitches named C in any octave can be played in the chord and at least one of those Cs must be played. Finally, notes that are a minor seventh above F are named Eb, so any of the pitches named Eb in any octave can be played in the chord and at least one of these Eb's must be played as part of the chord. The different ways that a chord can be rearranged are called voicings. Hear four different voicings of F7 chords in quick succession.. A pitch in a chord can be transposed to any octave wihout changing the chord type Chord types Major chord types Major chords have a consonant sound that many people would describe as bright-sounding, cheerful, happy and harmonious. In chord progressions they tend to be used as resting places for melodies and as the goal chords of long successions of chords. Major triad A major triad includes notes from three different classes of pitch: the root, the major 3rd and perfect 5th. This is the most relaxed, most consonant chord in all of harmony. Listen to four different C major triads. The chord symbol for a major triad is just the name of the root with no chord type modifier. For example the chord symbol Db specifies that the major triad built on Db using the pitch classes Db, F and Ab should be played. Major 7th A Major 7th includes notes from four different pitch classes: the root, the major 3rd, perfect 5th, and major 7th. It uses the same pitch classes as a major triad but adds a fourth class, the major 7th. The chord symbol for a Major 7th is Ma7. Example: the G Ma7 chord specifies a chord whose root is G which uses notes drawn from the B, D and F# pitch classes. Listen to four different C Ma7 chords. Major 6th A Major 6th includes notes from four different pitch classes: the root, the major 3rd, perfect 5th, and major 6th. It uses the same pitch classes as a major triad but adds a fourth class, the major 6th. The chord symbol for a Major 6th is Ma6. Example: the G Ma6 chord specifies a chord whose root is G which uses notes drawn from the B, D and E pitch classes. Listen to four different C Ma6 chords. Minor chord types Minor chords are considered to be the dark counterparts to the bright-sounding major chords. Minor chords can be used to give listeners a feeling of sadness, disturbance, or darkness. These feelings are especially pronounced when the minor triad and minor 6th chords are sounded. These feelings are accentuated even more, when a minor chord is the goal chord that sounds at the end of a progression. The minor 7th, a four note chord, contains a three note minor triad two of whose pitches overlap a major triad that is also part of the minor 7th. Because of the major triad that sounds within the minor 7th chord, it feels less dark than the minor triad sounding by itself. Minor triad (mi) The minor triad includes the root and perfect fifth like the major triad but instead of including a major 3rd it includes the minor 3rd.The chord symbol for a minor triad is "mi". Example: the D mi triad specifies a chord whose root is D which uses uses notes drawn from the F (minor 3rd) and A (perfect fifth) pitch classes. Listen to four different Cmi triads. Minor 7th (mi7) The minor 7th chord (mi7) includes the root, minor 3rd and perfect 5th of the minor triad and adds a minor 7th interval. Example: the D mi7 chord symbol specifies a chord whose root is D which uses notes drawn from the F (minor 3rd), A (perfect 5th) and C (minor 7th) pitch classes. Listen to four different voicings of the Cmi7 chord. Minor 6th (mi6) The minor 6th chord (mi6) includes the root, minor 3rd and perfect 5th of the minor triad and adds a major 6th interval. Example: the D mi6 chord symbol specifies a chord whose root is D which uses uses notes drawn from the F (minor 3rd), A (perfect 5th) and B (major 6th) pitch classes. Listen to four different voicings of the Cmi6 chord. mi7(b5) The minor 7th chord with a flatted 5th (mi7(b5)) changes the perfect 5th of a minor 7th chord to be a diminished 5th (flatted 5th). Example: the B mi7(b5) chord symbol specifies a chord whose root is B which uses uses notes drawn from the D (minor 3rd), F(diminished 5th) and A (minor 7th) pitch classes. Listen to four different voicings of the Cmi7(b5)chord. Dominant chord types Dominant chords have a relatively dissonant sound that gives listeners the impression that a chord progression is visiting an unstable place and should soon move to a more consonant, more restful sounding chord. How dominant 7th chords differ from major 7th chords Dominant 7th chords add a minor seventh harmonic interval to a major triad. A major seventh chord adds a major seventh harmonic interval to the major triad. Despite the fact that these chord types share the heritage of the major triad, they mean entirely different things to listener's ears. The major seventh feels fairly restful because the harmonic intervals formed between notes of the chord are pretty consonant. Between the root and perfect fifth and between the major 3rd and major 7th, intervals of the perfect 5th are formed. Between the Root and major 3rd and the fifth and the major 7th, major 3rds are formed. These are the most consonant harmonic intervals used in music. The major 7th actually adds an edgy feeling to the chord, but it usually can't overwhelm the other consonances that sound in this chord. The dominant 7th feels unsettled and restless. Between the major 3rd and minor 7th in the chord, the harmonic interval called the flatted fifth is formed. In the Middle Ages this interval was called the devil in music and was banned from ecclesiatic music. The interval between the perfect 5th and minor 7th is a minor 3rd, which also has a dark unsettled feeling. Dominant 7ths are rarely places in a chord sequence where the melody pauses. When a 7th is playing, that's usually the place where the melody is most active and also the place where the more unusual harmonic intervals are formed by the melody notes. They are the points of maximum tension in a chord sequence and almost always are followed by a chord which relaxes the tension. The tension relaxing chords are frequently a chord from the major or minor familes whose root is a perfect 4th above the root of the dominant 7th chord. The one exception to this is that blues tunes are almost always built predominantly using dominant chords. Blues tunes move from one tense dominant 7th chord to another. The objective of a blues is to allow the performer to invoke blue notes, special harmonic intervals which were banned from Western music hundreds of years ago. Playing two dominant 7th chords whose roots differ by a perfect 4th in the certain pattern used in blues, provide a support that make it easy for the performer to find and the listener to hear these blue intervals. Dominant 7th (7 chord) The dominant seventh chord (symbol is 7) includes all of the notes of a major triad (root, major 3rd, perfect 5th, and adds a minor 7th. Example: the G 7 chord symbol specifies a chord whose root is G which uses notes drawn from the B (minor 3rd), D (perfect 5th) and F (minor 7th) pitch classes. Listen to four different voicings of the C7 chord. Listen to four different voicings of the C7 chord 7sus The suspended 7th chord has the root, perfect 5th and minor 7th intervals of a dominant 7th chord but substitutes a perfect 4th for the major 3rd that would be played in a dominant 7th. Example: the G7sus chord symbol specifies a chord whose root is G which uses pitches drawn from the C (perfect 4th), D (perfect 5th) and F (minor 7th) pitch classes. Listen to four different voicings of the C7sus chord. 7b9 The 7th with flatted 9th chord is a five note chord which adds a b9 interval to a dominant 7th chord. A b9 interval is an octave plus a minor 2nd, so we are actually adding tones from the class of intervals that is a halfstep higher than the root. Example: a G7b9 specifies a chord whose root is G and which uses pitches drawn from B (major 3rd), D (perfect 5th), F (minor 7th) and Ab (b9). Listen now to four different voicings of the F7b9 chord. 7(#5) The 7(#5) chord has the root, major 3rd and minor 7th intervals of a dominant 7th chord but substitutes a augmented 5th for the perfect 5th that would be played in a dominant 7th. Example: the G7(#5) chord symbol specifies a chord whose root is G which uses pitches drawn from the B (major 3rd), D# (augmented 5th) and F (minor 7th) pitch classes. Listen to four different voicings of the C7(#5) chord. 7(b5) The 7(b5) chord has the root, major 3rd and minor 7th intervals of a dominant 7th chord but substitutes a diminished 5th for the perfect 5th that would be played in a dominant 7th. Example: the G7(b5) chord symbol specifies a chord whose root is G which uses pitches drawn from the B (major 3rd),C# (diminished 5th) and F (minor 7th) pitch classes. Listen to four different voicings of the C7(b5) chord. Augmented chord types augmented (+) triad The augmented triad has the root, major 3rd and augmented 5th intervals. A C+ chord has a root of C which uses pitches from the E (major 3rd) and Ab (augmented 5th) pitch classes.Listen to four different voicings of C+. Ma7(#5) The Major seventh chord with augmented fifth Ma7(#5) adds a major seventh interval to an augmented triad. The intervlas used in the chord are the root, major 3rd, augmented 5th, and major 7th. Listen to four different voicings of C Ma7(#5). Diminished chord types dim The diminished triad (dim) has the root, minor 3rd and diminished 5th (b5) intervals. A Cdim chord has a root of C and uses pitches from the Eb (minor 3rd) and Gb (diminished fifth) pitch classes.Listen to four different voicings of Cdim. dim7 The diminished seventh (dim7) chord adds a double diminished seventh (ie. a major 6th) to a diminished triad. A Cdim7 chord has a root of C and uses pitches from the Eb (minor 3rd) , Gb (diminished fifth), and A 9major 6th) pitch classes. Listen to four different voicings of Cdim7. The Chord Grid The SongTrellis Music Editor has a dialog called the Chord Grid that makes it super easy to find new chord progressions. The Chord Grid dialog displays a rectangular array of little squares. To the left of each row of squares in the array is the name of a type of chord. There are twelve squares in each row each of which displays the name of one of the pitches that fit in one octave (C, C#, D, D#, E, F, F#, G, G#, A, A#, and b). Touching one of the squares with a mouse causes that square to be selected and shown with a black background. When you select the square labelled D in the row labelled 7sus, this means that you have selected a D7sus chord. When you press the Play button in this dialog, an arrangement of a D7sus chord is calculated and played for you. By clicking in different squares and pressing Play you can get a feeling for what chords sound good after one another. The cool part about this is that SongTrellis generates a different voicing for the selected chord type every time the Play button is pressed. So you get an idea of the different faces each chord can present to the listener. By default the chord roots in each row are arranged in ascending chromatic sequence starting with C. There is a dropdowm menu however that allows you to change the order in which the chord roots are arranged in the rows of the grid. You can ask for the roots to be displayed in the cycle of 4ths or fifths, in descending chormatic order, or in cycles of major seconds, minor thirds, major thirds, or flatted fifths. This is also cool because then you can very quickly what it sounds like to hear all of the different types of chords played in varoius cycles. These cycle motions catalog and characterize all of the different sensations you can get by moving from one chord to another. I'm going to program a version of the Chord Grid for the SongTrellis site. It will work in a more clumsy fashion than the version in the Editor and will be much slower. I'll also have to restrict the number of voicings presented for each chord type to four or five instead of the unbounded number that's available in the Editor. If you'd like to see this, send me encouraging mail (davidlu@songtrellis.com) so I work on it faster. If you're a Mac user and would like to use the Editor, send me mail and sign up as one of my beta testers.

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