  
3
Identifying
natural intervals
In this lesson, we will consider intervals that have no accidentals--natural
intervals (located on the white
keys of the piano). It is easy to identify natural intervals
based on the number of natural half steps they contain. Remember
that natural half steps occur between E-F and B-C. The following
example presents some natural intervals. Each interval contains
either 1, 2 or no natural half steps. Study
these examples carefully and see if you can determine how many natural
half steps are in each.


The
following rules can be used to identify natural intervals: |
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seconds and thirds (2, 3):
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M2/M3 have 0
natural half steps
m2/m3 have 1
natural half step
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P4 has 1
natural half step
A4 has 0
natural half step
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P5 has 1
natural half step
d5 has 2
natural half steps
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sixths and sevenths (6, 7):
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M6/M7 have 1
natural half step
m6/m7 have 2
natural half steps
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unisons and octaves (1, 8):
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all are perfect
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As you can see in the chart above, the fewer the natural half steps,
the larger the interval. Vice versa, the more natural half steps
contained in an interval, the smaller the interval.
Notice on the keyboard that there is only one fourth (F-B) which
contains no natural half steps and only one fifth (B-F) which contains
two natural half steps. The rules for fourths and fifths can thus
be stated:
The following method is recommended for recognizing intervals without
accidentals:
- Determine the number size
of the interval.
- Determine the number
of natural half steps that occur within the interval.
- Label the interval
quality based on its number size and the number of
natural half steps it has (e.g., a 6th with one natural half step
is Major).
Let's revisit the four intervals from the top of this page. What
is the size and quality of each?
 
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