Everything about Enharmonic totally explained
In modern
music, an
enharmonic is a note (or key signature) which is the
equivalent of some other note (or key signature), but spelled differently. It is the same exact note or key with either of two possible names. For example, in twelve-tone
equal temperament (the modern system of
musical tuning in the west), the notes C and D are
enharmonically equivalent - that is, they're represented by the same key (on a
musical keyboard, for example), and thus are identical in pitch, although they've different names and
diatonic functionality.
In a given
diatonic scale, an individual note name may only occur once. In the
key of F for example, the major scale is: 'F, G, A, Bb, C, D, E, (F)'. Thus, the 'B' is called 'Bb' rather than 'A#' as we already have a note named 'A' in the scale. The scale of F# major is: 'F#, G#, A#, B, C#, D#, E#, (F#)'; thus we use the term 'A#' instead of 'Bb' as we need the name 'B' to represent the 'B' note in the scale, and 'E#' instead of 'F' as we need the name 'F' to represent the 'F#' note in the scale.
All
key signatures also have an infinite number of enharmonic key signatures that sound the same. The most common interchanges occur between key signatures with more than 4 sharps or flats. For example, the key of B, with 5 sharps, is enharmonically equivalent to the key of Cb, with 7 flats. Keys past 7 sharps or flats exist; they are, however, normally impractical, and are enharmonically equivalent to keys with fewer sharps or flats. The key of Ab, with 4 flats, is equivalent to the key of G#, with 8 sharps, the first of which is double-sharped (order of sharps: Fx C# G# D# A# E# B#).
Tuning enharmonics
The modern musical use of the word
enharmonic to mean identical tones is correct only in
equal temperament. This is in contrast to the ancient use of the word in the context of unequal temperaments, such as
1/4 comma meantone intonation, in which enharmonic notes differ slightly in pitch. It should be noted, however, that enharmonic equivalences occur in any equal temperament system, such as
19 equal temperament or
31 equal temperament, if it can be and is used as a
meantone temperament. The specific equivalences define the equal temperament. 19 equal is characterized by E♯ = F♭ and 31 equal by D♯♯ = F♭♭, for instance; in these tunings it's
not true that E♯ = F, which is characteristic only of 12 equal temperament.
In 1/4 comma meantone, on the other hand, consider G♯ and A♭. Call middle C's frequency
. Then high C has a frequency of
. The 1/4 comma meantone has perfect major thirds, which means
major thirds with a frequency ratio of exactly 4 to 5.
In order to form a perfect major third with the C above it, A♭ and high C need to be in the ratio 4 to 5, so A♭ needs to have the frequency
» . Such small differences in pitch can escape notice when presented as melodic intervals. However, when they're sounded as chords, the difference between meantone intonation and equal-tempered intonation can be quite noticeable, even to untrained ears.
The reason that — despite the fact that in recent western music, A♭ is exactly the same pitch as G♯ — we label them differently is that in
tonal music notes are named for their harmonic function, and retain the names they'd in the meantone tuning era. This is called
diatonic functionality. One can however label enharmonically equivalent pitches with one and only one name, sometimes called
integer notation, often used in
serialism and
musical set theory and employed by the
MIDI interface.
Enharmonic genus
In
ancient Greek music, the
enharmonic scale was a form of
octave tuning, in which the first, second, and third notes in the octave were separated approximately by
quarter tones, as were the fifth, sixth, and seventh.
An
enharmonic is also one of the three Greek
genera in music, in which the
tetrachords are divided (descending) as a
ditone plus two
microtones. The ditone can be anywhere from 16/13 to 9/7 (3.55 to 4.35
semitones) and the microtones can be anything smaller than 1 semitone. Some examples of enharmonic genera are
» 1. 1/1 36/35 16/15 4/3
2. 1/1 28/27 16/15 4/3
» 3. 1/1 64/63 28/27 4/3
4. 1/1 49/48 28/27 4/3
» 5. 1/1 25/24 13/12 4/3
Enharmonic tetrachords in Byzantine music
In
Byzantine music,
enharmonic describes a kind of
tetrachord and the
echoi that contain them. As in the ancient Greek system, enharmonic tetrachords are distinct from
diatonic and
chromatic. However Byzantine enharmonic tetrachords bear no resemblance to ancient Greek enharmonic tetrachords. Their largest division is between a
whole-tone and a tone-and-a-quarter in size, and their smallest is between a
quarter-tone and a
semitone. These are called "improper diatonic" or "hard diatonic" tetrachords in modern western usage.
Further Information
Get more info on 'Enharmonic'.
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