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In lecture two, Zack and I described the
concept of keys and key signatures.
You'll remember that when we travel
through the octave using
scales, we get distinctive internal
patterns of intervals that arise.
And you'll remember the major scale has
that distinctive
pattern of tone, tone, semitone, tone,
tone, tone, semitone.
>> And you remember us talking about key
signatures and
saying that they're a way for us to signal
right
in the very start of a piece of music,
what
sharps and what flats we're going to have
in any given key.
This came from the idea that some scales
were built up, and we needed to
use some sharps and some flats when we
were using a tonic that wasn't C.
So, this then allows us to use any one of
our pitch
classes, and that is any one of the 12
note names as
our tonic, so that we can build patterns
of tones and semitones
or scales, or melodies or chords in any of
these given keys.
Now, it'll help you, when you're trying to
become fluent in reading
and writing music, to try and get these
memorized as much as possible.
If you look back at week two, there are
some tips
and mnemonic devices for how to actually
go about doing this.
>> Okay so, at the start of this lecture,
we were looking
at triads, and we were looking at
perceptual effect of those note groupings.
So that one, just one of the notes that
was there, was the more important one, was
the one we can use to identify that triad,
had that overarching label for that triad.
Well, within a key, the relationships
between and
within those triads and how we use them
can
also contribute to that overarching sense
of tonality,
by which we mean the quality of the key.
>> So we've been using words like harmony and
harmonic structure.
And these are words and phrases that you
hear when we're talking about music often.
What do I actually mean by these phrases?
Now is a probably a good time to actually
think a wee bit more precisely about we're
saying.
>> Yeah.
Well, harmony describes the effect of
those triads that we've been talking
about.
And the relationships and the patterns
between the
triads when we use them in a key.
Key and harmonic structure, or key and
harmony, are the two
most important building blocks for music
that sits in a tonal tradition.
So to explain this more, I'm now going to
sing you a familiar
tune; you can follow the melody on the
stave notation on the screen.
Instead of using the words that you'll be
familiar with, I'm
just going to use the scale degree numbers
when I'm singing.
[MUSIC]
One, one, five, five, six, six, five.
Four, four, three, three, two, two, one.
Five, five, four, four, three, three, two.
Five, five, four, four, three, three, two.
One, one, five, five, six, six five.
Four, four, three, three, two, two, one.
[MUSIC]
You can hear a couple of things, a couple
of features in that familiar song.
The first one that we're going to point
out,
is that you got a very strong tonal
identity.
[MUSIC]
I was singing in C.
[MUSIC]
And C is the tonic.
And it came across very clearly.
>> Another thing we can think about
relates to the structure of the music.
So as the melody progresses, there are
points.
It comes to rest, but it doesn't feel
completely finished.
There are other points where the music
comes to
rest but does feel finished and does feel
'closed'.
Now these points are what we know as
cadences.
>> Let's look at a couple of those
cadences from the familiar song.
A cadence that comes to rest but sounds
open and unfinished.
We've got one up above the world so high,
like a diamond in the sky.
[MUSIC]
It rests, but it's not finished.
And we can compare that with the return at
the end.
Twinkle, twinkle little star, how I wonder
what you are.
[MUSIC]
What's causing that effect then?
>> Well, in order to think about, we
really want to look at the scale degrees
again.
Before we do that, let's just think about
the key of C as a whole.
So we got, one, two, three, four, five,
six,
seven, and back to one again for our
tonic.
>> We know that triads that are built on
the tonic.
[MUSIC]
And the dominant.
[MUSIC]
Have particularly strong structural
properties, harmonically, they're very
strong.
So let's see which scale degrees feature
in the dominant triad.
[MUSIC]
We've got a five.
[MUSIC]
And we've got a seven.
[MUSIC]
And we've got a two.
[MUSIC]
I mean, we've got the fifth and the
seventh and the second degrees of the
scale present.
For the tonic triad, we've got the first,
and
the third, and the fifth degrees of the
scale present.
>> So let's go back to our melody again
and look at this in a bit more detail.
Well, if we look at one of the points that
the music came to rest but didn't feel
finished, we get.
>> We had five, five, four, four, three,
three, two, five, five, four, four, three,
three, two.
>> So the five and the two really stand
out to us, and that's what gives us
that feeling - of it not feeling quite
finished,
the two notes that belong to the dominant
chord.
>> Especially when we compare that to the
phrase that did sound finished.
Four, four, three, three, two, two, one.
>> And when we're coming down there, we're
coming back away from the tonic chord.
Sorry... we're coming back from the DOMINANT
chord back to the the tonic chord.
And this is another example of a cadence.
>> So music theory, we call those cadences
where we
sit and hang around but at the dominant
open, unfinished chord.
We call that an imperfect cadence.
We contrast that with a perfect cadence.
And that's where we've traveled back from
a dominant.
[MUSIC]
Chord back to the tonic.
[MUSIC]
And we've come home again.
There's a lot more to say about cadences.
And we'll go a bit further in this lecture
later
on, but you'll go further still in the
final lecture.
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