Kpopalypse is back with more music theory! In the previous episode I discussed key signatures, but I didn’t really talk about what a “key” is, or what it means, so that’s what this post is going to be all about. Please read on and enjoy!

Almost all sound has a pitch, and when I say “almost all” I mean “all but one”. The one type of sound that doesn’t have any specific pitch is “white noise”, which is a mathematically equal random distribution of all audible pitches. Here’s what white noise sounds like.

White noise sounds like a television on a non-broadcasting channel. As soon as you change the distribution of pitches in white noise so it’s not 100% random/equal anymore, you actually have “pink noise”, which has a frequency bias of some kind. Most of the “relaxing white noise” YouTube videos out there are actually pink noise, where they’ve fine-tuned some of the noise out to be more “relaxing” or whatever. The reason why some people listen to white (or pink) noise to relax, is that if you give your ears a reasonably random low-volume distribution of all frequencies to listen to while you go to sleep, your ears actually stop listening and completely shut down. The result is that you wake up with very refreshed ears the next day. Or so I’m told anyway, I’m not bored enough to try this hippie shit.

Anyway, since (almost) all sound has pitch, we can represent these pitched sounds on the musical stave, and most humans hear these sound pitches “relatively” rather than “absolutely”. This is a very important point, that is essential to understanding everything else about how people perceive music. Think of pitch perception as similar to speed perception. Speed is always measured relative to a certain point in space. How fast are you moving right now? If you’re reading this post on a bus because you’re traveling on the way home to stream the new Oh My Girl song, you might feel like the bus is moving at a certain speed, and if you wanted to, you could measure this speed relative to the road (which is what a traffic cop is interested in), or relative to the distance from your house (which is what you are interested in because your widescreen monitor and nice sound system is there).

However while you’re on the bus you are moving in other ways too, for instance the Earth is also spinning at a certain rate, and probably in a different direction to your bus, so you could add that to your speed equation relative to the center of the earth. On top of this, the Earth is moving around the Sun too, so you could factor this relative movement around the Sun, then there’s the fact that the Solar System is moving through our galaxy The Milky Way so you could measure speed relative to the distance from the galaxy’s center, but then our galaxy is also in a big cluster of galaxies that is also moving at another speed, relative to fuck-knows-what. However spending time thinking about all this seems silly – you just want to get home on your bus trip, so when thinking about your speed you disregard the extra speed information as that doesn’t really matter to you and you can’t really feel any of it anyway. It doesn’t matter that you’re moving at 460 meters per second of planetary rotation if your house is also moving at that same speed due to being stuck on the same planet, the planetary rotation is not helping you get home so you can stream the new Oh My Girl song, so the speed you care about is actually the speed of the bus, because while you are absolutely moving at many million kilometers per hour relative to the galaxy or whatever shit, only the movement of the bus is the movement which is changing your relative speed from home.

Humans perceive pitch in the same way, relative to a tonal center. How do humans define this tonal center? Usually – but not always, it’s the first note that they hear. There’s plenty of exceptions, so let’s take a look at some random songs so we can determine how the tonal center is perceived.

BigBang’s “Fantastic Baby” starts at 0:05 with a very strong and heavy low D note in the keyboards. This establishes D as the tonal center of the piece. When the singing starts, the first note of the vocals is also D, but that doesn’t really matter – the big D in the keyboards establishes D as “home base” before the singing even starts. Now everything else that you hear in the piece will be heard relative to D.

In the above, the top stave represents the vocals and the bottom stave is the synthesiser. They’re both just piano noises on playback in the video but that’s because I’m a lazy caonima and couldn’t be bothered changing the sounds.

All that repetition of the D (both staves start with a D) really grinds the D home as the starting key. Therefore the little run that happens in the fourth bar is perceived relative to the tonal center of D.

It’s not always this way. Let’s look at an example where the first note heard by the listener isn’t the tonal center.

T-ara’s “Wae Ireoni (Why Are You Being Like This)” starts with the vocals at 0:04. The first note in “Wae Ireoni” is also sung as a D, but then the vocal line moves up to F and then G. In this case G is actually the tonal center. How do we know that “Fantastic Baby” is in D but “Wae Ireoni” is in G, when both start with a D in the voice?

Observant types will notice that the very first bar of the piece is only one beat long instead of four. This little “mini-bar” at the start is called an “anacrusis“, and is used to show that the song begins with an extra beat before the proper start of the piece, it’s a little “lead-in” passage. Those first two notes don’t really count for establishing the tonal center because they’re very quick, the tune doesn’t stay on them long, and most importantly of all, they’re the “lead-in” so they don’t matter that much. When the actual first beat of the song hits, that’s when the piece has moved up to G, and at this point the synthesised bass has also started playing an ostinato (repeated phrase) on the note G as well. That’s how we know that G is the tonal center for this piece – the G gets “hammered home” at the start a lot more than the very fleeting D, even though the D comes first.

So that’s how to determine a tonal center. The next step is to determine whether a piece is in a major key or a minor key, and for that, we need to look at major and minor scales.

Above are a bunch of major scales, along with their corresponding key signatures. Each scale starts on a different note, however all of these scales are in fact exactly the same scale – the major scale. All major scales sound basically the same, because even though all these scales start on different notes, the relationship between all the notes is the same, as the notes in these patterns are equal distance relative to each other. The major scale playing in isolation has a kind of “happy”, “nursery-rhyme” sound, and the pattern that all of the above major scale patterns conform to is as follows:

Major scale – T T S T T T S

T stands for “tone“, a tone refers not to the note itself but the distance between two adjacent notes. A tone is a jump of two notes.

S stands for “semitone“, referring to “half a tone”, a jump of just one note.

The above example is C Major, which is the scale first taught to piano students because it is easy to play and to read due to having no sharps or flats in it. However every single major scale has the same tone-semitone pattern.

Above are some minor scales, with their key signatures. (These are all “natural minor” scales, not the stupid “harmonic minor” and “melodic minor” scales that classical students get taught, we’ll pretend those don’t exist for now). Minor scales have a different, more maudlin sound when played in isolation compared to major scales, and they also have a different tone/semitone pattern to major scales:

Minor scale – T S T T S T T

All (natural) minor scales share this same pattern, regardless of which note they start on or how many sharps and flats are in the scale.

So keeping all of this in mind, are “Fantastic Baby” and “Wae Ireoni” major or minor? Well, smart folks would have figured out just by matching the key signatures up that both songs are in fact in the minor keys of D minor and G minor respectively, but the fact is that you don’t even need to have those resources available or even committed to memory to know whether you’re dealing with a major or minor key. Because all music is relative to the tonal center, and all scale patterns have the same tone/semitone combination, all you need to do is work out exactly where your tonal center is, and then look at the types of note choices being made around that tonal center.

Above is the start of “Fantastic Baby” – look at the circled note, this note is F. F is a tone and a half above the tonal center of D. This gives away “Fantastic Baby” as a minor-key piece – because the minor tone/semitone pattern is T S T T S T T, whereas the major pattern is T T S T T T S, we know that a note in that position is a signifier that a minor scale is being used. On the other hand if the note circled was F# instead of F, we would know that a major key is much more likely, because F# is two tones (or four semitones) above the tonal center, which fits into the major scale T T S T T T S pattern.

Above is “Wae Ireoni” again. The F is circled again in the anacrusis before the first bar of the piece, but this time the F is in a different place in the scale. As we’ve worked out our tonal center is G, the F is the last step leading up to G. Since it’s normal F and not F# we once again know we’re dealing with a minor key. The minor pattern is T S T T S T T, wherewas major has an S at the end of the sequence so the final note of the scale before G would be F# instead. I’ve also circled the notes Bb in the second bar (remember these are flattened notes due to the key signature). Bb is a tone and a half above the tonal centre of G, this means that once again we’ve confirmed the pattern T S T T S T T, and not the major pattern T T S T T T S (where we’d just see a normal B instead of a Bb).

So that’s how to determine the key of a song:

Listen for an obvious tonal center

Work out what other notes are in the song by comparing them to the center (my relative pitch post may help if unsure)

Look at which scale pattern those notes fit into

Easy! There are some complexities here that I’ve deliberately left out or ignored to keep this post short and sweet, such as modes, modulations and different types of intonation, these can complicate things a bit but the above process works reliably a good 95% of the time for most popular music, and probably a good 98% of the time in k-pop specifically where almost everything is either major or minor with not a great deal of harmonic trickery.

That’s all for this post – Kpopalypse will return with more music theory at another date!