# Tag Info

11

There are four types of perfect interval: perfect unison, perfect fourth, perfect fifth, and perfect octave. These can be thought of as belonging to two groups. In the first group, all intervals of a unison or an octave are called perfect because the note is not changed. An octave is twice (or half) the frequency of the first note. The second group ...

9

My answer builds on the answer contributed by DR6. Based on your reaction to other very good answers posted here already, your question seems to boil down to: "Why do humans innately feel that certain intervals are consonant". And so much so that they are willing to call them "perfect". Before getting to that question, let's look at why Western culture ...

7

Since both of them are flat, it is the same interval they would be without flats. So: Bb - Eb would be the same as B - E which is perfect fourth. Bb - Ab would be the same as B - A which is minor 7th. Bb -Db would be the same as B - D which is minor 3rd.

7

"Is there a solid definition of perfect intervals, lying around somewhere I just can't find?" Yes. A "perfect" interval is an interval that is not one of minor, major, diminished, augmented.

6

Perfect intervals are the ones that don't have two forms: major and minor. C Db D Eb E F F# G Ab A Bb B C root minor major minor major perfect tritone perfect minor major minor major octave 2nd 2nd 3rd 3rd 4th aug/dim 5th 6th 6th 7th 7th ...

5

A “perfect” interval is one that has nice small integer frequency ratios in Pythagorean tuning. These are traditionally considered the most consonant intervals. P1 = 1:1 P8 = 2:1 P5 = 3:2 P4 = 4:3 Major and minor intervals have more complex ratios: M2 = 9:8 m7 = 16:9 M6 = 27:16 m3 = 32:27 M3 = 81:64 m6 = 128:81 M7 = 243:128 m2 = 256:243 ...

5

All intervals can be turned upside down.(Called inverted). Thus a C-E as a major third, when played E-C becomes a minor sixth. There is a 'rule of nine'.Minors become majors, majors become minors, augmenteds become diminisheds, etc. The exceptions are the octaves, 4ths and 5ths. (Unison doesn't count !) Those do not change their identities. A 4th of C-F ...

5

I use a simpler method; counting semitones. A major third has 4 semitones. So using your example I would think of A, then count up four semitones (Bb, B, C, C#) landing on C#. Interval, Semitone Count Unison, 0 Minor Second, 1 Major Second, 2 Minor Third, 3 Major Second, 4 Perfect Fourth, 5 Tritone, 6 Perfect Fifth, 7 Minor Sixth, 8 Major Sixth, 9 Minor ...

5

The answers provided here offer a useful trick, which is to quickly translate into a scale you already know to find the answer. For instance, if you know that C to E is a major third, then it must be the case that Cb to Eb is a major third and also that C# to E# is a major third, too. It's fine to use this trick when it comes in handy, but it sounds like ...

4

One trick you can use is to remove the accidental from your starting note in order to make it a more common major scale, and then add the sharp back to the answer at the very end. I'll use your example: I want a major 3rd above G# Using your method, I know the answer should be some kind of B Whoa, G# Major is a crazy scale! Let's pretend it's just a G G ...

3

Picking notes 'by ear' is only 50/50 if you are tone deaf. For those of us not tone deaf, this is something that will improve with practice, which is why the Ear Trainer was built in the first place. But, you do have a slightly increased chance of getting it wrong when descending, and there is a reason. The short answer is, it's music theory, and you need ...

2

Or, to put it another way, Νo. 10 -Bb- A is a major 7th, so to Ab is a minor 7th. No. 11 - Bb - D is a major 3rd., so to Db is a minor 3rd.

1

Use only the major scale as a datum point. As there are different minor scales, it will confuse the issue. Count up using sequential letter names to arrive at the right name. This will put the note on the correct line or space. For example, a major third above A#. A,B,C. Thus it's a C.Because A# key has loads of #s, the C will have to be Cx (C##).Yes, it's ...

1

With two choices for an answer, it's 50/50. Intervals are generally considered using the lower note as a basis. Thus C-D =maj 2, C-Db= min2. Using the first note heard (which is higher) as a datum point is unusual, as ears tend to gravitate towards the lower note as a start.Thus, I would hear , say C-Bb as a minor seventh, even though it is an octave out, ...

1

The name "perfect" may be a reference to a numerical coincidence, which makes the interval of 7 semitones very close to the ratio 3:2 of frequencies. 27/12 = 1.4983... 3 / 2 = 1.5000... Major and minor intervals are less precise: 24/12 = 1.2599... 5 / 4 = 1.2500... which may make them annoying to the sensitive ear, as if e.g. your guitar is slightly ...

1

All the rest have answered in terms of high-level music theory concepts, but I think it can be interesting to look at the intervals as raw coefficients instead. Harmonic intervals between notes are the intervals that can be expressed with simple rational numbers, where a "simple" rational number is one with a small amount of small prime factors. For ...

1

Doubly-diminished intervals will seldom occur in a piece whose tonal center remains in one key. Weird things can happen when pieces modulate, however, especially if the most "natural" way of writing the modulation would result in an excessive numbers of sharps or flats. Consider, for example, a piece of music that starts in E major and modulates upwards ...

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