Finding scale from notes

Question

I am self learning guitar and I've learned to play scales all over fretboard by finding root position but it isnt working in practice (as expected) e.g.

I start by finding notes and right pitch of a song just by listening. A song I figured out uses these notes A A# G F D C (4th string, 10fret). First off almost every song plays extra random notes here and there, not respecting major minor step difference which can be too tough to quickly figure out when trying to improvise.

Secondly I cant tell which one is key note because I dont know which scale uses exactly these notes. If there isn't any scale with these notes, how improvisation can work as I stick to pattern of a scale.

Note: I can construct Major and minor scales (using half,whole steps)

Answer 1

The first thing you should always try is to have only one of each note-letter name in your key. Thus, if you have an A and no B but you have an A#, then you should rename the A# to Bb, so there is only one "A" note. If you do so in this case, then you have a key signature with Bb and the rest of the notes natural. That matches F or Dm. (Please note: this is not to say that this technique always works, particularly in blues or jazz, but it is the first technique you should try if the notes don't make sense.)

A great many songs do stay in a single major or minor key. Almost all of the ones that don't, they move out of the key in a precise or at least non-random manner. Unfortunately, modulation and moving outside the key are not really beginner concepts in music theory. Thus, it can seem very confusing. But most people who continue in their music education are able to grasp the concepts over time.

Answer 2

Let's first sort those notes and use Bb instead of A#, so we have only one note derived from A:

F G A Bb C D

If you add an E to those six notes you have the F major (or D natural minor) scale. If instead you add an Eb, you get Bb major (or G natural minor).

Answer 3

I think you would benefit from spending some time studying scales that are not related to any particular song.

The reason for this is that songs, particularly instrumental tunes but also vocal ones, often have notes that are not included in the principle scale. These are called accidentals (though they are quite deliberate).

You will also discover that tunes often pass through several keys. I am not referring to key changes that are indicated by a new key signature but key changes that come about because of movement in the harmony. For example:

Suppose you have a song in the key of C major. Somewhere in this tune the composer has written a C7 chord. Even though it is called "C7" this chord belongs in the key of F major. Effectively the composer has caused a key change.

Take an old song like Sweet Georgia Brown (The Harlem Globetrotter's theme song). This tune has 2 measures of E7, 2 of A7, and 2 of D7 in the opening phrase. Each dominant 7th chord implies a key change. You will not find the key signature changing every 2 measures however. This would make the score unreadable. But the musician who has studied his or her theory understands this movement of key changes.

Jazz musicians call these key changes 'Key Centers' and understanding this helps some jazz players memorize the chord changes to a colossal number of songs.

I don't want to confuse you with theory. What I have tried to do is illustrate a couple of reasons why it makes sense to study scale theory both in the context of songs, and out of it.

At the very least you should try to be aware that scale theory in song context may not be as pure as scales in isolation.