[MUSIC] I hope you are feeling comfortable with major and minor keys. Remember that the tonic of a minor key is three half steps and two letter names down from the tonic of the relative major. B flat major, G minor, C sharp major, A sharp minor, and so on. Relative major and minor keys share exactly the same key signatures at diatonic notes, officially, that is. But there's one more thing to learn about minor keys. Listen to this excerpt form Bach Suite No 2 for solo cello in D minor which I'm having my computer play. Remember, D minor and F major have the same key signature, one flat. You should hear right away that it is in minor with this, [SOUND] or this, [SOUND] as the tonic and these as the first six notes of the scale that it's built from. [MUSIC] You may have noticed that one note is not what we would expect if we were using the diatonic scale given by the key signature. Notes should be, [MUSIC] C, [SOUND] D [SOUND]. But right from the very beginning, this note, [SOUND] Is being replaced with this note, [SOUND]. So there are the notes being used. [MUSIC] B flat, [SOUND] C sharp, [SOUND] D [SOUND]. The altered note is the seventh note of the scale. Instead of the diatonic seventh scale degree C natural, [SOUND] Bach uses the raised version C sharp, [SOUND] To create a half step between seven, [SOUND] and one, [SOUND] Just as happens in major. As a result, in the first three measures, the Cs are C sharps. This change, raising the seventh scale degree to create a leading tone that is a half step from the tonic, is almost always done in minor, especially when the next note is the tonic. Raised seven is much more common than diatonic seven. Traditionally, this use of raised seven is called harmonic minor. Leaving seven unchanged is called natural minor. Natural minor and harmonic minor are two of the three forms of minor. Here's what a D natural minor scale sounds like. [MUSIC] So those are the notes that are in the key signature with just one flats. Otherwise, everything natural. Here's what a D harmonic minor scale sounds like. [MUSIC] With the seventh note of the scale raised from C [SOUND] to C sharp [SOUND]. We don't say that a piece is in harmonic minor or natural minor. We just say, for example, the Cello Suite No 2 is in D minor, even though it uses almost all raised seventh scale degrees. Notice that this melody suggests a new key in the fourth measure, at which point we start seeing C naturals. One of the ways to tell if a piece is in major or minor when you're looking at the score is to look for these raised seventh scale degrees. The C sharps are a big clue that we're in D minor and not F major at the beginning. When the C sharps turn into C naturals later on, it's a clue that we have left D minor. The seventh scale degree as almost always raised in minor. It's important to remember that the key signature does not tell you the key of the music, only the notes do. For example, consider these two short passages. All the notes are exactly the same except for B naturals in the top passage and B flat in the bottom passage. That is, the diatonic B flats have been raised a half step. Here's what the passages sound like, the top passage with the B naturals. [MUSIC] And the bottom passage with the B flat. [MUSIC] The top one seems to be implying C minor as the key. [MUSIC] This feels like the tonic. [SOUND] The bottom one seems to be implying E flat major is the key. [MUSIC] This feels like the tonic all because of one changed note. Let's try one. What note would be altered in the harmonic minor scale that has four sharps? The major key would be E major. The relative minor is C sharp minor. The seventh scale degree is B natural in natural minor. Raising it gives us B sharp. So it sounds like this. [MUSIC] We can't call it a C natural, because C sharp is the name of the key. What note will be raised in the harmonic minor scale that has five flats? Do is the second to last flat, D flat. La, the tonic of minor, is down three half steps and two letters. So, it's B flat minor. The seventh scale degree in natural minor is A flat. [MUSIC] There's our A flat. To make it harmonic, we have to raise it a half step [SOUND] to that. So A flat become A natural. Scale sounds like this. [MUSIC] How would you write a G sharp harmonic minor scale? We need to go up three half steps to find the tonic of the relative major. So G sharp to A, A to A sharp, A sharp to B. B is the relative major, so the key signature for G sharp minor is five sharps. The first six notes of the scale agree with the key signature. [MUSIC] It's the seventh note where the change happens. And this is where it gets tricky, because originally the seventh note is an F sharp. [SOUND] In order to raise it, we have to call it an F double sharp. [SOUND] It sounds like a G natural, but we still have to call it some kind of an F because G is already taken. This is probably the most common use of double sharps, raising the seventh scale degree of harmonic minor scales. Sometimes when composers write a minor scale, they want to avoid the sound that arises from raised seven. [MUSIC] This interval here is actually three half steps, which sounds awkwardly huge in a scale. [MUSIC] So it's not uncommon to find the sixth scale degree [SOUND] raised also, [SOUND] creating a scale that sounds like this. [MUSIC] This is called a melodic minor scale. In a way, it's like a hybrid between major and minor. It has the characteristic lowered three of minor, [MUSIC] And the characteristic five, six, seven, one of major. When going back down, its not as important to have a half step between seven and one. So seven and six are lowered back to their natural minor notes. [MUSIC] The official definition of the melodic form of minor is raised six and seven going up, natural 6 and 7 going down. Let's practice one. What would the altered notes be in an ascending, that is going up, F melodic minor scale? If F is the tonic of the minor scale, we can find the relative major by going up three half steps and two letter names. F [SOUND] to F sharp [SOUND], F [SOUND] sharp to G [SOUND], G [SOUND] to A flat [SOUND]. The key signature of A flat major is B, E, A, D flat, one more flat than the tonic note. So an F natural minor scale is F [SOUND], G [SOUND], A flat [SOUND], C [SOUND] [SOUND], D flat [SOUND], E flat [SOUND], F [SOUND], four flats. If we raise seven, we get E natural [SOUND]. Raise six to get D [SOUND] natural. Going down, the E would go back to E flat and the D would go back to D flat. So here's the F melodic minor scale. [MUSIC] And going back down. [MUSIC] To summarize, there are three forms of minor scales. Natural minor, in which the notes are all the same as the relative major but with a different tonic, harmonic minor, in which the seventh scale degree of the minor scale is raised, and melodic minor, with raised six and seven going up, lowered six and seven going down. We're now done with the unit on key signatures and minor scales. In the next unit, we'll take a closer look at intervals. [MUSIC]
