Now that we know what intervals are and understand how they work, let's switch things up and try inverting some intervals! 🥳 Wait...but what does that mean? In simple terms, interval inversion is basically just an interval that has been flipped upside down!
To invert an interval, the lower of the two notes is moved up an octave so that it is above the former top note. Or vice versa, take the upper note and bump it down an octave, then it'll be below the former lower note.
Here's an example of a major third (F-A) being inverted:
Notice how we now have a new interval? By applying the interval identification skills you learned in the last chapter, you can tell that this interval must be a minor sixth because it spans 6 lines and spaces, and 8 semitones! However, this isn't the only way to reach this conclusion, and it is not the quickest either. There are a few rules of interval inversion that you can follow to determine the inversion more efficiently.
The Rules of Interval Inversion 🙃:
➡️the two interval sizes will add up to nine (eg. a major 3rd inverts to a minor 6th, 3+6=9)
➡️major intervals invert to minor intervals, and vice versa
➡️augmented intervals invert to diminished intervals, and vice versa
➡️perfect intervals invert to perfect intervals
Let's look at a few more examples of inversions on a staff:
Your turn! Practice inverting these intervals by using the tricks above (answers at the end of the chapter):
Next up: Compound Intervals!
So far we have learned about simple intervals, which are intervals within an octave. But now we are going to venture past the octave and dive into compound intervals. These are the intervals that are larger than an octave.
Here are a few compound intervals:
Compound intervals can be a bit tricky to identify because it's difficult to quickly recognize or count them. Instead we can break them into octaves and simple intervals so that they are much easier to handle.
Let's take the perfect 13th in the example above and go through the process of identification together.
This diagram displays the process of identification step-by-step. Firstly we need to divide the interval at the octave, which in this case is the D. We can now see that this compound interval is made up of an octave (D-D) and a perfect 5th (D-A). The value of these intervals are then added together to find the size of the compound interval (8+5=13). And finally, the quality of this interval is determined by the quality of the simple interval. So the 13th must be a perfect 13th!
🦜 Polly wants a progress tracker: Can you identify the interval that spans from an F# to the B an octave above? What about a G that reaches to the Db two octaves above?
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