I am trying to solve some practice questions and was wondering if they are right My answers :-
- Key: D Major 4th Interval
- Key: A-Flat Major 2nd Interval
- Key: G-flat Major 3rd Interval
- Key: B-Flat Major 2nd Interval
- Key: E Major 2nd Interval
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Your keys are correct. The "interval" as I recall is defined as the change in pitch or frequency starting from the lower note going up to the higher note. It doesn't matter what the key is (I'm referring to 12TET tuning only).
For example in the key of C the pair of notes (C, G) are a perfect 5th (not a major 5th), but so are the pairs (D, A), (E, B), (G, D), (A, E). These are all perfect 5ths. One way to identify intervals is to count half steps (h); 1h = min2, 2h = Maj2, 4h = Maj3, 7h = P5.
To get the correct interval name you need to be aware of a few things.
2nd, 3rd, 6th, and 7th can be Major or Minor but the 4th, 5th and octave are referred to a perfect. Any note and itself (same octave) are called unison.
Perfect intervals can be flattened or raised by that is referred to a diminished and augmented respectively. Actually the other intervals can be augmented too. I believe that if a minor interval is flattened again it is referred to as diminished.
The interval is judged relative to the lower pitch note relative to the key you are in.
This is important when you have enharmonic tones. An example of this in 12TET tuning in the key of C is (C, Gb) and (C, F#). The first is a diminished 5th and the second is an augmented 4th. They are the same to the ear by strictly speaking they should have different names. The reason is that the letter name identifies the numerical name of the interval (related to the degree of the note relative to the lower note) while the accidental identifies the action being applied to that degree. So (C, G) is a 5th because G is sol relative to C, and the "b" applied to the G causes it to be diminished. Symbols for the different interval types are as follows,
Major = M
minor = m
Diminished = d or dim, or "o"
Augmented = aug or +
Perfect = P
Lets take the first one as an example. You are in the Key of D major. The notes are (E, Ab). A is the 4th of D, in other words the pair (E, A) is a 4th (Perfect). The flat lowers the 4th making it dim 4th (enharmonic to a M 3rd, but that would be the wrong name). The next 2 are easier since there are no accidentals. The second pair is (C, Ab). A is the 6th of C but this is a half step lower due to the key signature so it would be a minor 6th. Not an augmented 5th since the letter name of the 5th of E is B.
One way to get the letter name correct is to simply use the musical alphabet
A B C D E F G A B C D E F G ... etc
Grab the sequence starting at the lower note and count up until you get to the second note. For the last example grad E F G A B C D E and count 1 = E up to C = 6 so the interval is some type of 6th. Then count the half steps to determine if it's a Maj or min 6th. I am not suggesting that C is the 6th of E in the key of E. The above is just a simple algorithm to always get the correct number name of the interval.
The half step to interval equivalence is...
1h = m2
2h = M2
3h = +2 or m3
4h = M3
5h = P4
6h = +4 or dim 5
7h = P5
8h = +5 or m6
9h = M6
10h = +6 or m7
11h = M7
12h = P8 or Octave
You can try the others keeping in mind that the x = ## (a double sharp).
I hope that helps.