I am playing a song in D Major, and it contains an Am. How do I notate this in roman numerals?

Question

I am learning music theory and I was told to transcribe some songs and also note the chords as roman numerals.

The song I have is in the key of D Major, but contains an A minor, which to my understanding is not part of this scale. The V of D Major would be an A Major, right?

So, I went on a google search bonanza and read some things about "altered chords". And since A Major became A Minor in my example, I guess that is what it is since it is the third that has been flattened. So, can I note this as I v IV for the progression "D Am G"?

Answer 1

I v IV would be correct, because what seems to be going on here is that you have 'borrowed' a chord from D natural minor scale. The v from the D natural minor is Am, and it is common to borrow chords from the parallel minor scale (scale with the same name); (the same happens when you are in the minor scale; you can borrow a chord from the major scale)

Answer 2

With a lower case v

minor chords are indicated in our figured bass with smaller case roman letters and the Major chords with upper case roman letters.

So I --> i for the tonic chord

II --> ii for the super tonic chord

III --> iii for the mediant

IV --> iv for the Sub dominant

V --> v for the Dominant

Vi --> vi for the Sub mediant

and lastly Vii --> vii for the leading tone chord.

Just remember that the Major Sub dominant and Dominant chords have to have two horizontal line going above and below them. That part of the notation gets lost when we use the computer but when writing a figured bass of your own they should include it.