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  • In this lesson I’m going to talk a little bit more about dissonant intervals.

  • Since you already know quite a bit about intervals by this point,

  • you can use your knowledge of the previous lessons to solve some of these problems.

  • So I’m going to write up here dissonant, and these are going to be seconds and sevenths.

  • Like the consonant intervals, youre going to have major and minor,

  • and if you got bigger you’d have augmented, and if you got smaller you’d have diminished.

  • So what happens if you want to make a minor second down from here?

  • If we think about it on the keyboard, it seems really easy, so I’ll show you that.

  • Here’s an F sharp, and were wanting to make a minor second down.

  • That’s easy to play, we know it’s right here, it’s F.

  • Now the problem with this is, if were thinking of this as F sharp and this as F,

  • those are the same letter names so it can’t be a second, because a second

  • would have to be an F sharp to some kind of an E.

  • That’s okay though, we can kind of recreate that E as

  • let’s call this an E sharp, and now it’s going to work.

  • Let’s look back up on the board here. Here’s our E.

  • We know we need some kind of E because it’s says second,

  • and then minor means that we need one half step.

  • If we leave it like this, just a plain E natural, were actually going to have two half steps.

  • So minor second, is just the same as a half step.

  • So, I’m going to put this in front of it.

  • That’s nice to know that a minor second is the distance of one half step.

  • If we do it here on the board, I’m going to pick this one, I could do either one,

  • I’m going to pick this one and I’m going to wrap it around, over this, to the next octave.

  • I’ll take that away. If we count, weve got one, two, three, four, five, six, seven.

  • And two plus seven is going to add up to nine. It always has to add up to nine.

  • So now we know this isn’t right anymore.

  • We had a minor second down, and now we have some kind of a seventh going up.

  • We also know from before that minor intervals are going to invert to major intervals.

  • Theyre just going to go the opposite way.

  • Let’s listen to that on the keyboard.

  • You want to listen to the relationship between that minor second and that major seventh.

  • We had this, this was our original interval like that, an F sharp down to an E sharp.

  • Then we took that bottom note and flipped it around

  • so this note is going to want to go all the way up here.

  • Notice this is almost an octave, if I did this it would be an octave,

  • so major sevenths are almost octaves. Theyre pretty wide intervals,

  • and theyre really dissonant. That one has a certain kind of dissonance to it.

  • That minor second has more of an agitated dissonance because the notes are so close together.

  • So now were going to try a major second.

  • I’m going to do a B flat, and a major second down from that.

  • We already know it’s going to be some kind of an A, because we need

  • to count two letter names or were not going to get the right thing.

  • So some kind of an A.

  • Now, just from thinking about what the piano keyboard looks like,

  • I know that B flat down to A is just a half step.

  • That’s not going to be big enough. I need two half steps to get a major second

  • because major seconds are going to be like a whole step.

  • As far as the distance is concerned.

  • If this isn’t big enough, I’m going to widen it by putting a flat in front of that.

  • So what I’ll do is just invert that.

  • Maybe this time I’ll take the top note and flip it around.

  • Again, I’m just inverting it.

  • It was a major second down, so it should invert to minor,

  • second should invert to seventh, like this.

  • I should have a minor seventh, and let’s look at that on the keyboard again.

  • Here’s my B flat and I go down to an A flat to get that major second.

  • I’m going to take that B flat and I’m going to put it down the octave,

  • and there’s a minor seventh.

  • It has a more mellow dissonance to it, as does the major second

  • because they are so related, they are inversions of each other.

  • It has this special name because it used to really shock people when they heard it,

  • so they had to come up with their own special name for it.

  • People abbreviate it like this, this is really common and it looks like pi,

  • but it’s actually because the two T’s tend to run together.

  • If you see this, it just stands for tritone.

  • Let’s try figuring out how we get that. A tritone can be two things,

  • and I’m going to show you one of them, and then I’ll show the other.

  • So I mentioned a little bit before about how sometimes B and F

  • can be troublesome when youre trying to write perfect intervals.

  • That’s because when you have either F up to B or B up to F

  • on the piano keyboard, you automatically get that tritone sound.

  • Let’s look at how that works. On the keyboard, here we have F up to a B.

  • It’s just a fourth, one, two, three, four, but this is going to give us that dissonance.

  • Any other fourth that were going to play on the white keys is just going to be perfect.

  • Here's that dissonant one again, and if we keep going, they're all perfect again.

  • The same thing is true with fifths. If we make a fifth by going from B to F, same thing as the F to B,

  • theyre just in different octaves, were automatically going to get a tritone.

  • All the other fifths are all going to be perfect.

  • Let’s look back up on the board here.

  • So this has got to be some kind of a fourth, because if we count, we get four.

  • However, it’s not a perfect fourth because a perfect fourth should

  • only have five half steps, and tritones always have six half steps.

  • When you count them on the piano keyboard youll see that.

  • Sometimes I like to think that instead of six half steps, I like to think three whole steps.

  • Sometimes that’s easier.

  • I’m going to take this, it was perfect, if I had done something like this it would be perfect,

  • but since it’s not, perfect intervals, when they get bigger, become augmented.

  • So, F to B, F natural and B natural becomes an augmented fourth.

  • You could also write like this, that would be fine. Or even just a four, but I’ll be using this one.

  • This is an augmented fourth, and of course if we invert it,

  • were going to get four plus five equals nine, so this is a fifth.

  • When you invert an augmented interval, the opposite of that is diminished.

  • Now this is kind of an interesting one.

  • You see were inverting these, these are kind of the opposite qualities,

  • we see four and five adding up to nine. Then, six half steps here.

  • If the half steps add up to twelve, this is also six half steps.

  • So any of the other intervals that you invert, youre going to get different numbers of half steps.

  • But if you invert a tritone, youre going to get 6 no matter what.

  • When we do this, the first thing were going to worry about is the number, right there.

  • I know that fours look like there’s going to be one on a line and one on a space, so this is what a fourth looks like.

  • I’m not worrying about this part yet. Actually what I want here is a diminished fifth.

  • Here, theyre both going to be on the same thing, theyre both on a line,

  • or they're both on a space whenever youre writing a fifth.

  • So now all I have to do is make sure I have six half steps in each one.

  • Like I said before, sometimes it’s easier to think about this being three whole steps.

  • Maybe we can look at that on the piano.

  • The first one, we were going to write an augmented fourth up from here.

  • We have this so far, but this is definitely not augmented yet, it sounds to perfect.

  • I’m going to count whole steps this time, and I could three of them, one, two, three.

  • I’m going to need a C sharp, but I’m not going to change my letter name

  • because I specifically wanted to do a fourth.

  • I’m going to keep it as a C sharp and not a D flat or anything like that.

  • Now when we write the diminished fifth down from A,

  • were going to use the same strategy we used over here.

  • Let’s go over to the piano.

  • Here’s our A, and were going to count three whole steps down.

  • Here’s one, here’s two, and then three is going to take us here.

  • On the board originally when we didn’t know what our accidentals were,

  • we had this, which was actually a perfect fifth.

  • Were going to need to sharp that D to get six half steps or three whole steps,

  • which gives us that diminished fifth. It’s going to look like this.

  • That’s it for this lesson.

In this lesson I’m going to talk a little bit more about dissonant intervals.

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A2 初級

音樂101:不和諧音程 (Music 101: Dissonant Intervals)

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    songwen8778 發佈於 2021 年 01 月 14 日
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