If chords progressions belong to more than one key, would tonality come from the melody?

Question

In popular music, lets say I have a song that appears to be in C major. The progression could be something like C > Em > Am > G.

This progression could also be in G major However. So, let's say we look at the melody but only the C major pentatonic scale is used and the F# or F is absent which would have been able to tell us the tonality of the song.

As a last resort, is it possible to listen to where the notes of the melody fall to get an idea of the tonality. For example the phrase could end on the G note on both the Em chord and the G chord. This kind of gives you the feeling that the song is actually in G not in C even though the chord progression starts on C and uses chords from the diatonic C major scale. Does music work in this way? I mean, the G note does feel like home in this case even without a more unambiguous chord progression being used so my question is: Surely the melody is just as much a determining factor not only in terms of which notes are used but also on what note the melody ends. Is this correct?

Answer 1

In popular music, lets say I have a song that appears to be in C major. The progression could be something like C > Em > Am > G. This progression could also be in G major However.

The key isn't just a question of what the chords are - it's about the note (and tonic chords) that the piece seems to come home to. So with one phrasing, C > Em > Am > G could be fairly clearly C major. With another phrasing, C > Em > Am > G could be clearly G major. A key isn't usually something you use to describe an abstract collection of chords - it's something that describes an actual piece. When you listen to the phrasing of the actual piece, it may make it clear where the piece comes home to.

Of course it's also true that a certain phasing and articulation of those chords might still leave the 'home note', and therefore the key, ambiguous...

is it possible to listen to where the notes of the melody fall to get an idea of the tonality

...but yes, as you say, the melody may change the feeling of the piece such that a particular home note becomes clear. In fact Every aspect of a piece may have an effect on what the key of a piece is perceived as - even things like the accenting of the notes and the volume of individual parts can have an effect.

And remember that ultimately this is subjective - two people might hear the same piece and perceive a different home note. Unless there's a statement from the composer about the key that you want to take as definitive, the key of a piece can be a matter of opinion.