I am NOT a fan of scary movies.
But I do like their soundtracks. "Halloween" is a horror classic, and the haunting, jarring piano theme is iconic.
The song uses dissonance to make the listener feel uncomfortable. Dissonance is just a fancy term for a lack of harmony. It sounds clashy -- like it shouldn't go together.
It might sound unpleasant, but it's a lot of fun to play. And it's really easy, once you figure out a few little things.
The Hardest Part - 5/4 Time
The first thing you'll notice when you look at the music is the time signature. It's in 5/4 time.
What the heck is 5/4 time?
5/4 time just means that we have 5 beats in a measure, instead of the normal 4. And each beat is a quarter note. Because this song uses 8th notes, we'll be playing 10 eighth notes in every measure.
The Main Theme
When you look at parts of the music, this song can appear difficult. but it's very easy. The entire right-hand melody is just a series of 5ths with a half-step added at the end.
The opening line uses C# and F# as the fifths, and we move up a half-step to D at the end of every measure. This pattern will repeat throughout the entire song. The notes will change, but the interval and rhythmic pattern remain the same. If you can remember that, the song becomes WAY less daunting.
Modulation - Changing Keys
A key feature of this tune and the element that provides all the dissonance is modulation. This is just another fancy word for changing the key signature in the song.
Take a look at measure 7 on line 3:
There are a lot of accidentals going on here. Now -- instead of playing C# and F#, we have shifted everything in the right-hand down a half-step.
So we are now playing C natural and F natural (C and F).
But the pattern is the same. The interval is still a fifth, with a half-step up at the end (this time a C#).
This happens for the rest of the song.
Creating The Ominous Left Hand
On the music, the left hand just plays long, single notes. We often hold them over several measures.
To add even more gloom to the song, try playing the left hand as octaves.
And that is all there really is to it.