What determines the key for the melody

How do you know what the correct key is for a song / melody? Thanks.

It is usually the 1st chord in the song. For example, if the progression starts with a C chord then it’s the Key of C. If the starting chord in the progression is a minor chord then you have to use a minor scale. This doesn’t mean you need a minor scale harp, it just means you have to do an extra conversion. Key of Am is the same as C so if the song starts with an Am you would probably want to use a C harp or an F harp. The system used to figure out what major key to use when playing a minor key is called the circle of 5ths. Google it and you should find some good diagrams.

Things get tricky when the song stars with a 5th chord rather than a major or minor. Then you either have to guess and check, or simply investigate the other chords in the progression. If the 1st chord is C5 and the second is Eb then you know it’s probably the key of Cm because the C major scale doesn’t have an Eb in it but the Cm scale does.

You will find the odd song that doesn’t start with it’s root chord. This is not normal but does sometimes happen so if you can’t seem to find the right notes when basing your harp on the 1st chord then try basing them on the 2nd chord and then the 3rd. This won’t happen often but it will happen.

Hey WPM, do you understand what Rockmonkey is saying?
Do you read music or understand theory? If not, read on.
If I am oversimplifying, just ignore me.
If this Rockmonkey is the same as the Rock Monkey Guitars
from the UK, I have enjoyed checking out your site. Good work.
OK WPM, there is no magic wand to determine the key of a tune
if you don’t have a trained ear or a partial understanding of music
theory.
Get started on recorded music so the song won’t be gone before
you get there. Stop and start the piece at will, and then start
over when you get to the correct harmonica.
One good idea is to use a pitch pipe with the note names marked
on the pipes. Listen to where the music “comes to rest” or “returns
home.” Think of the “Do, Re, Mi…” scale. “Do” is home. It starts
and finishes the scale. This scale is actually the simplest form of
a melodic phrase (a song). It begins by establishing the starting
point and ending point (home) for the phrase. If you stop singing
before you get all the way from “Do” to “Do,” the musical thought or
phrase will seem unfinished. This is because the melodic line “pulls”
toward home (this tone or note called tonic in relation to the other
notes of the scale or tune). The melody will continually return to tonic
in order to feel finished. Music is made up of stress and relief moments.
The stress moves away from tonic, and the relief moves toward it in
usually practical patterns. Listen for these returns to home, and you
will generally have your pitch. Match it on a pitch pipe, and read the
note marking the pipe. Get the harmonica keyed to the position in which
you want to play, and try it out.
This book has been entitled “Finding the Key for People Who Are Not Dummies And Don’t
Want to Sound Like Them.”
I know I didn’t go over anyone’s head here. I just hope I didn’t hit anyone in the foot.

thebugleboy

Yeah, that is me, and thanks