Did you have a set of plastic building blocks as a kid? Every box has a picture of a super cool project on the front – maybe a house or a robot or a motorcycle. When you open the box and dump the pieces on the floor, you realize that there are WAY more blocks than you need to build the motorcycle from the picture. In fact, the options are endless! You pull out the instructions and begin separating the pieces that you need for the motorcycle, leaving unnecessary blocks piled up on the side. Use the right pieces and your creation will be just as cool and exciting as the picture on the front of the box! Use the wrong pieces and… well, who knows what you’ll end up with.
When writing and playing music, you can use a key to determine which pitches will sound good in the song and which ones will not. Just like the instructions for your building block project, a key helps you separate the pitches you need from the ones you don’t. When you know the key of a song, you can choose from the pitches within that key to write melodies, play solos or build chords without concern that you will hit a sour note. Keys are built from a tonic note and chord. They can be major or minor.
Tonic note and chord.
The tonic note (also called the root note) is the note from which the key is built. It is the note that gives its name to the key. For instance, the tonic note for the key of A major is A. A tonic note is just one pitch and cannot be classified as major or minor. However, the tonic chord identifies the major or minor character of the song.
A major key is built from the major diatonic scale with the designated tonic note. Song in major keys have a happy or fulfilled character to their sound. A major key will use the whole and half steps from the major diatonic scale to determine what pitches fit in the key. In the key of A major, the pitches that work in the key would be A, B, C#, D, E, F# and G#.
A minor key is built using the natural minor key with the designated tonic note. Songs in minor keys have a sad character to their sound. A minor key will use the whole and half steps from the natural minor scale to determine what pitches fit in the key. In the key of A minor, the pitches that work in the key would be A, B, C, D, E, F and G.
How to determine the key of a song.
The most precise way to determine the key of a song is to read the key signature. If you do not know how to read a key signature, you can look at the first chord and the last chord in the song.
Songs often (but not always) start and end on the tonic chord for the key. When a song ends on the tonic chord, it is said to be resolved; it gives a sense that everything is over and the song is wrapped up. If the song ends on a chord other than the tonic chord, it is unresolved and feels suspended. An unresolved ending gives the sense that something else is supposed to happen, as if the song is not complete.
If the first and last chord in the song are the same, this is the tonic chord and its root note is the tonic note for the key. If the first and last chords are not the same, determine if the ending of the song sounds resolved. If it does, then the last chord is the tonic chord. If the ending of the song feels suspended or unfinished, then the last chord is not the tonic chord and the first one probably is.
It is important as a musician to be able to determine the key signature of a song and play the notes and chords that fit within the key. Listen to some of your favorite songs and try to determine the key of the song.