hey, welcome to 12tone!
when we talk about chords, the first thing we tend to mention is triads, and with good
reason.
they're pretty much the simplest possible harmonic devices out there.
a lot of music has been made from them, and most of that comes down to a group of triads
I like to call the big 4: there's major, (bang) minor, (bang) diminished, (bang) and augmented,
(bang) and, again, that makes sense.
these all share a structure: they're two thirds stacked on top of each other, which creates
a lot of interesting interactions between their notes.
they might use major thirds, minor thirds, or a mix of the two, but in the grand scheme
of things it's a pretty limited group, isn't it?
well, good news!
there's more triads out there.
lots more.
before we dive in, let's get our definitions straight.
when I say triad here, I'm referring to any collection of three notes played as a chord.
some theorists prefer to call this a trichord, reserving the name "triad" only for those
stacks of thirds we saw earlier, but other theorists insist that a trichord is actually
something completely different.
the whole thing's a bit of a mess, so I'm just picking a term and sticking with it.
so yeah.
triads.
three notes.
let's go.
actually, hold up.
I mentioned before that triads are the simplest possible harmonic devices, and that's not
quite true.
that honor belongs to the power chord (bang) which is just a root and a perfect fifth.
the power chord is an incredibly stable sound, and it's a great tool for adding, well, power,
but from a theoretical perspective it's kinda boring.
it's not like it has any clever structures holding it up, it just doesn't contain enough
acoustic information to sound wrong.
triads, then, may not be the simplest chords, but they are the simplest interesting ones.
anyway, after the big four, probably the next most popular triads are the sus chords.
sus chords, short for suspended chords, are where we take a regular triad and replace
the third degree with another note, usually the four.
(bang) these are pretty unstable, and most often they resolve back to the regular triad
you modified.
(bang) you can also replace it with the second degree (bang) making what's called a sus 2
chord, which I think is especially effective if you resolve to a minor triad.
(bang)
but sus chords are still pretty standard for modern music.
they're modifications of normal triads, not really their own thing.
another option that's a little more adventurous is to take the stacking idea and replace the
3rds with something else entirely.
for instance, we could go up by 2nds, (bang) 4ths, (bang) or even 5ths (bang) although
that last one is kinda just a sus 2 chord again but more spread out.
these are a little further outside of our harmonic comfort zone, and they're really
great tools for evoking complex ideas and emotions.
you can still sort of analyze them like they're modified versions of regular triads, but if
you arrange them right, they have a really unique sound.
another triad with a… unique sound is the Viennese trichord.
(bang) this was a popular tool among students of the Second Viennese School, a group of
composers who were just super into the idea of dissonance, and you can see that in this
triad.
it has all sorts of gnarly intervals, like the minor second (bang) and the tritone.
(bang) it's got a lot of different uses, though, and depending on how you arrange the notes
you can get some pretty interesting sounds out of it.
for instance, you can make it into a stack of fourths (bang) as long as you're willing
to count this augmented fourth here, or you can turn it into this almost-consonant thing
(bang) which sneaks in a perfect fifth for a little stability, although it's still not
very pretty.
or if you want something a little more functional we can turn it upside down (bang) which looks
kinda like an extended dominant chord (bang) with a couple notes missing.
and then there's shell voicings.
here, I'm stretching the definition a bit, so bear with me.
shell voicings are seventh chords, which we tend to think of as kind of the opposite of
triads.
a seventh chord is what happens when we take one of our normal stack-of-thirds triads (bang)
and add another third on top.
(bang) this gives us a fourth note, so clearly these aren't triads, right?
well…
I mean yeah, but here's the thing: the notes in a chord aren't all equally important.
the biggest deal is, of course, the root.
if you don't play that then you've got a different chord entirely.
after that, the next most important are the third and seventh degrees, collectively known
as the guide tones.
these are what give your chord its specific quality or sound, so you need to make sure
they're there too.
this is why the power chord feels so empty: it's got no guide tones.
but the fifth degree? that's optional.
well, most of the time, anyway.
the perfect fifth is so stable and so consonant that, if you don't play any fifth at all,
the ear will just assume that a perfect one was supposed to be there.
it'll fill the note in, so you don't actually need to include it.
and if we take that out, we get a shell voicing built out of a root, a third and a seventh,
which is three notes and, thus, a triad.
sort of.
but ok, we could keep listing more and more variations on the theme, each one more tenuous
than the last, but let's just skip ahead to the end.
how many possible triads are there?
well, here we need to turn to an old friend, Forte Numbers.
this is a method of grouping different collections of notes into sets, figuring out which ones
are basically the same as other ones, so we can figure out exactly how many different
kinds there really are.
and, fortunately for us, those sets are usually arranged by number of notes anyway, so it's
really easy to find out how many we've got.
it turns out there's 19 different 3-note sets, but does that mean there's only 19 possible
triads?
I wouldn't quite say that, thanks to one last twist: inversions.
you see, the way the human brain processes chords puts a huge emphasis on the lowest
note.
we saw this with the Viennese trichord earlier: each new bass note gave us a pretty different-sounding
result.
so each of those 19 sets can have one of three different roots, giving us 57 total triads.
well, actually 55, 'cause the augmented triad is a jerk.
it's symmetrical, so no matter which starting note we pick, we just get another augmented
triad.
but that's still not a complete answer, because with more common chords, inversion doesn't
really change how we hear it.
this, (bang) this, (bang) and this (bang) all pretty much sound like E major, even if
there's some variation between them.
and, of course, many of these potential triads are just harsh, dissonant nonsense.
(bang) so how many possible triads are there?
I suppose that depends on how you want to draw the lines.
anyway, thanks for watching!
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