Key signatures in music can help guide us when playing music or writing songs. They let us know what notes are available, what chords are available, different harmony’s we can use and whether the overall tonality of the song/ piece is major or minor.
When playing with others, you may hear things like, “what key is this in?” or “can we change keys down a third?”. Knowing the framework of keys will allow you to understand these questions and play accordingly. There are really no hard and fast rules in music but knowing the key you’re in provides a good set of guidelines to give you some options to play with.
We use key signatures to tell us.
- What notes are in the key?
- What sharps and flats are in the key
- What chords are in the key?
- If they key is major or minor
Songs often stick to one key as our ears find this familiar and pleasing hearing the notes that are all from these common intervals and harmony’s. though there are key changes where songs will completely change key to evoke a certain feeling or emotion. Borrowed chords are used from different keys or relative keys and many more options that ‘break the rules’ of being in a key.
But to break the rules we must first learn them. So, today well go over what a key is and how to find the notes and chords in that key, so we have those guidelines ready with us when we need them.
Major or minor?
A key is either in major or minor. The name of the key will always have a note whether that’s A, C or G# or whatever, this will be the root note of the key. Then it will have major or minor.
Tip: if they don’t specify major or minor it is often major and when it is a minor key it will specify minor E.g. G = G major, G Minor = G Minor.
How to find the notes in the key.
When we know the root note and whether the key is major or minor, we can use simple formulas from the root notes working our way up to find the notes in any key. These formulas just the terms whole step and half step. A whole step is 2 semi tones (two notes e.g. A to B) and a half step is one semi tone (one note up e.g. A to B flat). These formulas are:
Major: Whole, whole, half, whole, whole, whole, half
Minor: Whole, half, whole, whole, half, whole, whole
So, we take the root note and apply the corresponding formula to it to get our notes in the key. This works for any key starting from any note. Here are a couple examples to show you using the D major and the D minor scales.
Chords in a key.
Now that we have the notes of the key, we can find the chords available in the key too. we take the notes from the key starting from the root, these will be all of the root notes to the chords in the key. Then, we again apply a simple formula to them to find the chords functions (Major, minor, diminished)
Major key chords: Major, Minor, Minor, Major, Major, Minor, Diminished
Minor Key Chords: Minor, Diminished, Major, Minor, Minor, Major, Major
So, for each note in the chord working our way up from the root notes we apply these chord functions from the formula consecutively to get all the chords in our key. Here are a few examples to show you again, using the D major and D minor scales.
Ok but what key is it in?
If you can’t find what key a song is in or want to practice finding out without cheating and looking it up there are a few tricks to learn that will guide you to find what key the song is in. an easy way to make a guess is that a lot of songs will use the key center as the first and or last chords of the chord progression. This can be a good place to start to fond they key of the song.
Coming home
The key center of the song will generally sound like home in the chord progression. In the context of the other chords in the key, the other chords will have differing amounts of tension. Other chords in the key generally won’t feel resolved but when the progression comes back to the key center it will feel resolved and it will feel like home again. This is subjective and not a supremely accurate way of finding the key but can be useful to think about when listening to chord progressions.
Knowing the chord formula.
Let’s pretend for a second that were all practicing our ear training. So were listening to a song and we’ve found out the chords in the chord progression of the song but still can’t figure out the key. No worries. Let’s again pretend like we’ve been studying and know the chords in a key formulas, knowing these and using a little power of deduction we can often get a good idea as to what key we are in. here’s an example.
Example finding key signatures.
Say we have a song, and we find out the chords are A minor, D minor, F major and E minor. For a start we can see that there are two minor chords that are a whole tone apart (the D minor and the E minor). If we know our formulas we can deduct that there will only be one minor key and one major key where this will happen. In the minor key these will be the 4th and 5th chord. We then word backwards take the E minor, if we know that’s the 5th we go down a 5th to the one chord (key center) from there and that’s the A minor. There we go A minor is they key center and the first chord of the progression.
This technique takes a bit of practice and there are many other methods of deduction to use but it can be very helpful to find the key center and figure out what feel like home in the song.
Key signatures
Knowing they key of a song, how it lets you know the notes/ chords and how to find them is extremely helpful when playing and creating your own music. It is a major part of basically all songs and a framework around which they are built. Keep practicing and learning the formulas to commit them to memory and it will become a lot easier to learn songs you want to and create the songs you want to.
Learn the framework of the key and how to use it to your advantage. Then slowly learn how to break the rules of the key framework and create more tension in your music. Practice, explore and have fun.