What key is a song in?
The main focus of this lesson is to examine the question of "what key is a song in?"
Like every musician, also every guitar player wants to have perfect pitch, play by ear or easily determine what key a song is in. There are many ways to find the key of a song depending on what you have in your hand;
a music sheet with standart notation (time signature, key signature, accidentals...), just a tab of a song, or even just a record.
The first thing to help you while determining what key a song is in is the key signature. You have to know how to read sheet music and what the key signature means. The key signature is the number of sharps or flats that appear immediately after the clef. If your are not so familiar with key signatures and accidentals, I strongly recommend you to study this music key signatures lesson before you go any further.
For key signatures with sharps, the first sharp is placed on F line (for the key of G major/E minor). Subsequent additional sharps are added on C, G, D, A, E and B. For key signatures with flats, the first flat is placed on the B line, with subsequent flats on E, A, D, G, C and F. There are 15 different key signatures, including the "empty" signature of C major/A minor. Please look at the simple key signature worksheet.
|G Major / E Minor||F major / D minor|
|D Major / B Minor||Bb major / G minor|
|A Major / F# Minor||Eb major / C minor|
|E Major / C# Minor||Ab major / F minor|
|B Major / G# Minor||Db major / Bb minor|
|F# Major / D# Minor||Gb major / Eb minor|
|C# Major / A# Minor||Cb major / Ab minor|
You can see the key signatures and related keys above. I think you have noticed that each key signature refers two keys. For example one key signature for G major and E minor, one key signature for D major and B minor and so on. These key pairs are called as relative keys (relative minor or relative major of each others). Because two tones have exactly the same notes you can ask "How can I determine whether the tone is a minor or a major?" At this point you can check the major and minor interval rules and the chords used. Or just listen to the sound; if it sounds happy and cheerful probably it is a major and if it sounds sad and blue it is probably a minor.
Determining what key a song is in by ear requires ear training(or talent) and a little musical knowledge. Try to find the note which the melody keeps resolving to. This note called "root note". You can feel it, every time the melody reaches that certain note you feel relaxed and music resolves.
Play the song which you are trying to find the key of and play single notes on the fretboard until you find the one note that sounds best with the song. If you are having trouble finding it you may listen to bass notes. It will help.
You can test your "root note" by using your guitar to play a major scale in the "root note" key, while the target song is playing. If it sounds fine, your root note is correct. If not try the minor scale.
Leading tone (leading note)
Leading tone (leading note) is very important while determining what key a song is in. Leading tone points to the root note (tonic note). It is the seventh tone or degree of a scale that is a half tone below the tonic; a subtonic. Leading tone leads or resolves to the tonic. You also can feel the leading note while playing your guitar. When you play the leading note the music gains a tension and wants to resolve and when you play the tonic you can feel the resolving.
Take a look at the piece of music above. What key is the song in?
There must be a leading tone to the tonic if it is in a certain key. Using the key signatures chart above you can easily see that the excerpt should be in F major or in D minor. F major has a leading tone of E and D minor has a leading tone of C#. Because there is no C# in this sample we can say that the excerpt certainly in F major.
I hope that now you have an idea how to tell what key a song is in.