I want to pick up where I left off on the last video, at the fifth interval. From C to G sharp we have an interval with two names. It is either called an augmented fifth or a minor sixth. Most often it will be referred to as a minor sixth, although there are times you can call it an augmented fifth. What it is called has to do with chords and how they are put together, but that is a subject for another day.
The next interval going up the scale is between the C and the A. That is the major sixth interval. Up to the A sharp we come to the minor seventh interval. The minor seventh is an important interval because it makes up the dominant seventh chord. What is the dominant seventh? Well, in the key of C, the G chord makes up the dominant note (the fifth note of the key). It wants to push the ear back to the root, C. A G major triad, played with an added minor seventh interval pushes the ear even harder back to the C. Back in the C major scale, the C to A sharp interval creates a C Dominate 7 chord. So in the key of F, where the C is the dominate note, adding that A sharp note, that minor seventh, to the C major triad will push your ear back to the F.
The final interval is the major seventh. In the case of our C major scale, that is a B. The major seventh is a pretty jazzy sounding chord, if that is what you are going for. Of course, after the major seventh you come back to the root note at the octave.
Now I want you to do a simple exercise. Play each of the intervals so you can see how the interval sounds. Really pay attention to difference in pitch when you go from say, root to third and root to fifth, or root to second. The purpose of this exercise is to train your ear. Let's say you take a simple melody like Twinkle Twinkle Little Star. If you learn to hear intervals, then you'll be able to identify that first spread as a perfect fifth, the second as a second above that perfect fifth. Now, not only can you play Twinkle Twinkle Little Star by ear, but you can play it in any key you want!
Now let's try a few intervals on a less simple scale. We'll use A major. If we play A to B, we know it is a major second. Not just because we know the scale, and how intervals relate to that scale, but because we know how the major second sounds. If we play A to A#, we know it is a minor second because we know how the minor second sounds.
This type of ear training takes time. It doesn't come quickly, but if you make it a part of your daily practice routine, you will be surprised what you begin to hear when you listen to music. You may even begin to find yourself predicting where a melody will go, because you understand the inner workings of music.
If you haven't yet seen part one then check out part one of Intervals and Octaves here.