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So, last week,
we talked about intervals, and

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we said that this was
the space between notes.

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But really, to fully discover an interval,
we need two pieces of information.

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We, firstly, need the number of the
interval, but we also need the quality.

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So last week we looked at
the distance between C and E.

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[MUSIC]

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And we worked out that this was a third.

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C to D to E.

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One, two, three.

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But that's only half the picture.

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We say it's a third, but
we need to know the quality.

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We need to know what type of third is it?

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Mickey, what interval is this?

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>> One, two, three.

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That would be a third Zach.

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>> Okay.
And this one?

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>> One, two, three,
that's also a third Zach.

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>> Okay.
So these

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are two different intervals that
we're describing as thirds.

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And this is what we mean by quality.

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>> Take a look at this example.

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We're going to use our major scale
again as the reference point.

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We're going to be figuring out and

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naming all our intervals with
reference to the major scale.

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And this will give you a set of
interval descriptions that match

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music theory convention.

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So we're working from left to right.

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If we've got two notes that
are exactly the same pitch,

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we say that they are in perfect unison.

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The distance between the first and
second, the first and

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third, the first and sixth,
and the first and the seventh.

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Are all described as major second, third,

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sixth and seventh respectively.

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The distance between the first and fourth,
the first and fifth, and the first and

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the eighth, are called perfect fourths,
and fifths and octaves, respectively.

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So as we can see, in each case,

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we've got a description of
the quality of the interval.

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And in this case, it was either major or
perfect, and we also have the number,

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one, two, three, four,
five, six, seven, or eight.

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But as we've also said,
this is all based on the major scale.

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So what happens if we want to
work it into those that don't

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belong to the major scale?

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Well, firstly, we need to be aware that
there are other qualities of intervals.

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We've already talked about major and
perfect.

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We also have minor intervals, augmented
intervals and diminished intervals.

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>> So,
let's use an example to take this forward.

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On your screen, you've got a treble clef.

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And a D up to a C.

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The lower note is D.

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The upper note is C.

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So, let's count up from D: D,

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E, F, G, A, B, C.

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One, two, three, four, Five, six, seven.

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Seven steps.

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So we know we've got
some sort of a seventh.

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>> Okay.
So

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that's only have of what
we need to talk about.

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We've got the number now.

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We know it's a seventh.

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Now we need to think about the quality.

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Well, a really good way to do this
is to take the lowest note, and

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imagine that you are in the major key.

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Imagine that's the tonic of the major key.

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So in this case we're going to
imagine we're in the case of D Major,

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because the lowest note is a D.

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Okay.

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So we know that in the key of
D Major we've got an F# and a C#.

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Therefore, the 7th degree
of D Major would be C#.

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This would be a major 7th.

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We've already talked about this.

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Actually, this is a C-natural,

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which is a semitone lower than the C-sharp
that we would expect in this major key.

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When a major interval is made smaller,

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or lowered,
we say that this is a minor interval.

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>> So we've now seen
examples of major intervals,

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perfect intervals and
now we've had a minor 7th as well.

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But we've also mentioned such
things as augmented intervals and

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diminished intervals.

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So how would we get to 20 of those?

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>> Well, we've seen that the unison,
the fourth, and the fifth, and

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the octave are described
by the words perfect.

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And this is the cause of the constancy
between different types of scales.

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So they are called perfect.

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So if we have a perfect interval,

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and we raise it, we make that interval
bigger, we call that augmented.

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And if we make that interval smaller,
we call it diminished.

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>> So from a perfect interval,
is you step up one semitone,

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you've made that interval augmented.

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From a perfect interval that you
make smaller by one semitone,

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you've made that interval diminished.

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Now, music theory convention gives us
even more options if what we're starting

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with is a major interval.

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So if you remember, the second,
the third, the sixth, and

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the seventh intervals, were all originally
started from our reference point.

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As Major.

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Major 2nd, Major 3rd,
Major 6th, Major 7th.

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For any of those, if you were to
add one semitone to the interval,

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so make the top note higher,
sharpen it by one semitone.

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You would immediately get
to an augmented Interval.

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So for major you'd step up
one semi tone to augment it.

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From that same major,
if you were to step down one semitone, so

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you were to flatten the top
note by one semitone.

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You would get to minor,
as we'd already seen.

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Now, Zach, what would happen if you
were to take that minor interval and

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flatten it by one semitone again?

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>> Well, you're making it smaller, so

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again, we can say that that
interval is being diminished.

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[BLANK_AUDIO)