How to know key of a melody?

Question

How can you tell what key a melody is in if it uses notes found in multiple scales? And if a note is introduced from a different scale than the one it was in, does that change the key? What if it only plays 2 or 3 notes from the new scale? How many notes must a key be to actually make it a key and not just random intervals?

Answer 1

Keys can be confusing - are you looking to understand the accidentals within a melody and relate that to a mode? Fore example, play a simple melody like Ring Around the Rosie - this is based of a Major mode and therefore if you are playing in the key of C there will be no accidentals; but say you are playing 'Desert Sky' by U2 using the same tonal center as C - this mode is a mixolydian which now has a Bb instead of a B natural: the key is actually F, but the tonal center is on C. There is a complete course just learning the theory behind a melody.

Answer 2

Songs or passages of songs can have what we call key centers. Consider you are in Tampa, but you are also in Florida , and you are also in the U.S. So a song can be in D and have parts in Bb or A minor.

The song will always be in D and how many notes until it changes is up for discussion, for example how many brushes of red paint on something blue until we then call it purple?

Answer 3

Hello, the key is contained in the key signature shown in the treble clef. The key remains the same even if the melody steps out of the key from time to time. To better understand key signatures please google the Circle of Fifths. The chart shows the symmetry of key signatures. The key of C, or its relative minor of A, has no sharps or flats so there is no notation by the treble clef.

John

Answer 4

You can usually tell the key of a melody by looking at the ending, if you're in doubt. Most melodies begin and end on the tonic, or one of the other notes of the tonic triad.

Many melodies will change key areas briefly, only to go back to the original key. You probably wouldn't describe as being in a different key unless there's a cadence (major stopping point) in that new key.

Answer 5

I answered this same question previously, so I am copying and pasting my response here:

This is a great question, and it comes down to harmony.

In a lot of melodies we'll hear it start off on a certain pitch, and move away from that pitch before finally returning to it at the end. In those examples, it's fairly easy to discern what the key is as it's most likely that starting and ending pitch. But, what about when things aren't so clear, and like you say, it uses pitches that come from a few different scales? Well, we can tell what key a melody is in usually by the harmonies that a composer uses to support that melody. The harmony that we can hear the melody driving toward; where our ears finally feel a sense of resolution between harmony and melody, that is how we know what key a melody belongs to.

Introducing new pitches does not necessarily mean that the key has changed. When we hear that sense of resolution occurring with a different harmony than it previously did, then we can say that a piece has modulated. Typically we would expect a full harmonic progression from tonic area to predominant area to dominant area and back to tonic before we could say that something has truly modulated. Adding a few different notes could color a key, but not necessarily change it. For example if you were to borrow a few pitches from the parallel minor key you could change the overall sound of a passage without necessarily changing the key. This actually happens all the time in popular music, for example a "blue note" is technically a borrowed pitch, but using it doesn't mean that a song or melody has modulated.

Answer 6

This is a great question, and it comes down to harmony.

In a lot of melodies we'll hear it start off on a certain pitch, and move away from that pitch before finally returning to it at the end. In those examples, it's fairly easy to discern what the key is as it's most likely that starting and ending pitch. But, what about when things aren't so clear, and like you say, it uses pitches that come from a few different scales? Well, we can tell what key a melody is in usually by the harmonies that a composer uses to support that melody. The harmony that we can hear the melody driving toward; where our ears finally feel a sense of resolution between harmony and melody, that is how we know what key a melody belongs to.

Introducing new pitches does not necessarily mean that the key has changed. When we hear that sense of resolution occurring with a different harmony than it previously did, then we can say that a piece has modulated. Typically we would expect a full harmonic progression from tonic area to predominant area to dominant area and back to tonic before we could say that something has truly modulated. Adding a few different notes could color a key, but not necessarily change it. For example if you were to borrow a few pitches from the parallel minor key you could change the overall sound of a passage without necessarily changing the key. This actually happens all the time in popular music, for example a "blue note" is technically a borrowed pitch, but using it doesn't mean that a song or melody has modulated.