If I was to write an intro using only single notes, like Incubus’s Anti Gravity, how would I determine the key and which chords I could use? I look forward to your response! Hope you had a great weekend!
It’s difficult to give a clear answer to this really. I guess at it’s basic level most people might just find their way using their ears and just experimenting.
Sometimes the intro will come as an afterthought so the key and chords have already been established.
Another way might be that you are messing around with a particular scale and come up with a riff or melodic line. This would be pretty much the opposite, but same thing as coming up with the chords first, only this time the scale has established the key.
Things are rarely this formulaic, especially for pop music. My guess is the majority of musicians wouldn’t think about this on a purely theoretical basis. An intro can go anywhere you like, the transition from intro to start of song could be completely disconnected, you can’t really ‘formulise’ that.
Although there are compositional methods that can be used and are used by composers, it can be quite complex theory. Most of us don’t bother with it to that extent. I went down that road for a while but got bored if I’m honest and have since forgotten most of it.
If you know the intro riff in Anti Gravity you should reasonably easily figure out it’s a B minor riff, it starts around B and D (d is the b3) and includes F#, G and A for the most part. These set of notes alone could belong to a few different scales but listening to the song we can hear it starts with Bm. They could have used any method to come up with that but from a compositional point, it could have gone many other places.
I think this is one of those situation where just using your ears and experience is really all that matters. If you come up with an intro then either try to figure out what you hear in your head or just experiment. Also try to figure out the notes you play and what scale they might belong to.
Sorry, that was probably a bit long winded and not really answered much but hope it helps a bit.
