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All the common intervals (with the exception of
the tritone) can be found within the major scale. This example begins
on the tonic - the first tone in the scale - and
contains the ascending intervals based on it. Then, from the Perfect
Eighth - this is more often referred to as an octave
- the intervals are descending. |
The augmented 4th or diminished
5th is a rather unique interval. It is also known as a
tritone. All three names refer to the same sound,
but it can be written differently on a score. This interval is has
a leading tone "function" meaning to
it generally resolves to the third or fifth. |
Any other interval can be "augmented"
(raised another half-step) or "diminished" (lowered another
half-step) with the use of an accidental. Often these odd-looking
intervals are due to the logistics of composing and for the performer's
ease in reading the score.
Augmented 2nd = minor 3rd
These are called enharmonics. |
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Interval "Rules" in Writing:
- 2nds, 7ths - often heard in "nonharmonic"
passing tones, but also in 7th chords and more complex harmonies
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- 3rds, 6ths - make up the triads we hear in functional
harmony, also known as the 'consonant' intervals
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- 4ths, 5ths, Octaves - very open or 'hollow' sounding. The
general rule in composition is to avoid parallel movement, but
they can create an effective sound when desired. In other words,
for a theory class: Do NOT write in parallel perfect intervals
unless its approved.
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