Confused as to why one scale fits four different chords

Question

I'm learning the bass guitar. I'm looking at a song called "Bling Thing" in the Rockschool Grade 4 book. On YouTube in the bass guitar backing track this part begins at 0:48.

In this piece of music, there are four bars which are to be improvised.

The piece is in the key of E minor.

The chords are Em Am D7 B7

My music teacher said that with the exception of one note of B7 I could just play the E minor scale and it would fit all four chords.

I am baffled as to how this could be possible, surely they have different notes in them? For example, E minor contains E F# G A B C D but A minor does not have F#.

But when I play just the E minor scale up and down through the whole part it sounds OK to me!

This revelation came at the end of the lesson and there wasn't time to go into a lot of detail, but his explanation kinda overwhelmed me, so I will ask him to go into it more, but explaining the theory and getting my head around it is hard work that I would rather do away from the lesson as much as possible.

I wonder if anyone could explain or direct me to the relevant topic so I can begin to get my head around all of the theory for this. I play classical piano which never touched on chords and scales beyond rote memorisation, so some parts I am strong and some basic things I am weak at as I try to pick up this second instrument.

Answer 1

You seem to have confused the concepts of (1) chord, (2) scale, and (3) key. Your teacher gave you the E minor scale because of the E minor key, not because of the E minor chord. :) Confusing? Let's see:

The E minor chord, abbreviated as Em, has three notes: E, G and B.

The "E minor scale"... you probably mean the E natural minor scale. It has the notes E, F#, G, A, B, C and D. There are other minor scales like melodic, harmonic and jazz minor. Scales are just helper grids to help you reason about things.

The key of E minor means that the tonic chord i.e. the home chord is the E minor chord. If a song is said to be "in E minor", it just means that the E note is a central pitch in the song's harmony like the number 0 is a center in mathematics, and around that central E, notes are played so that an E minor chord would feel like a natural ending or resting state of that song. Because the notes of the E natural minor are so widely used in songs in the key of E minor, a key signature of one sharp (F#) is used in songs in the key of E minor (and its relative major key, G major). The E natural minor scale is a default scale in the key of E minor. Deviations from the default scale are marked with accidentals in staff notation. I assume you've seen accidentals and key signatures when playing piano.

Being in the key of E minor doesn't dictate any note or chord anywhere in the song, even though certain chords tend to be used very often. You can have a chord progression like Em - Am - B7 - Em - Dm6 - E7 - Am - F#7 - B7 - Em6, in a song that's in E minor, even though some of those chords contain notes that cannot be found in the E natural minor scale, or even any E minor scale at all.

The E natural minor scale is just a helper grid. Basic safe default pitches that are often used in songs in the key of Em. For technically oriented people, it could be called the factory default setting of notes for a song in E minor. But harmonic progressions can make chromatic alterations, like in the case of the B7 chord, which has a D# note. That means that the D note has to be made sharp, at least for the duration of that chord. In staff notation, this would be marked with an accidental.

But once more. A scale is a pitch grid that helps you locate cultural default expectations and often-used pitches. But a scale doesn't "sound" and it's not a law of nature. If the backing track plays a plain Em chord, you can play a loud and clear C# note over it with your melody instrument, and then the sounding total chord becomes Em6: E, G, B, C#. You changed the harmony. If you keep playing the C# for a long time, then it can even become an expected note. But if you then play a C natural instead, it will change the situation. But these changes or chromatic alterations do not change the key, if they do not change your feeling of what chord is a home chord. As long the E minor chord feels like home, you're in the key of E minor, regardless of what pitches the air is filled with.

In my opinion, to really learn how note combinations interact in harmony, you have to play chords by ear and try to reproduce the chord progressions you hear. For example, if you play a B major chord or a B minor chord in a song that's in the key of E minor, how it changes the feeling. You have to try both alternatives and learn to feel the difference.

The question "what notes fit where" is often answered with rules-of-thumb like "use this scale", for simplicity and to get beginners something to play that sounds sensible and isn't discouraging. I think that's what your teacher did. You're now supposed to just play notes from the scale and listen to what they sound like over different chords, without over-thinking it. Play and listen. Playing and listening is 90% of learning music. You learn by doing, not by thinking. When the time comes, you will encounter more concepts and different things to play and listen to. The more you've played and listened, the more you'll get out of the next lesson.

Answer 2

Chord tones and not chord tones

When improvising against any chord, the "primary" notes are those in the chord itself. Other notes are more or less decorative: adding color, passing from one chord note to another, or serving as embellishments to a particular note.

An example of chord tones and not chord notes and how to use them

Take an A minor chord as an example. It contains the pitches A, C, and E. In the abstract, when improvising and wanting to move from A to C, I could play A B C or A Bb C, among other possibilities. Which "in-between" notes I choose is heavily influenced by the overall key of the piece of music. So, when the piece is in E minor, I would likely choose A B C, because the B is part of the larger context: E minor. But for a piece in F major, I would more likely play A Bb C for the same reason.

Why can a chord work with a scale of a different name?

Any key/scale encompasses many chords. E minor, for example, contains the following triads (three-note chords):

       E F# G A B C D E ...
Em     E    G   B
F#dim    F#   A   C
GM          G   B   D
Am            A   C   E
Bm              B   D   F#
CM                C   E    G
DM                  D   F#   A  (C) ← (D7)

Thus, when a piece is in E minor and a sequence of these chords is encountered — such as Em Am D7 — one can "just play E minor, knowing that the chord tones will be contained within that scale, as will the intermediate tones.

Answer 3

Let's look at this a different way.

You are thinking that the notes from one scale maybe won't fit four different chords. How about if notes from that same scale won't even fit the root chord in question?

Key is Em. Play the 2nd, 3rd, 4th and 5th, or 4th, 5th, 6th and 7th - all in simple order, on the 4 beats, over the chord of Em. You may agree that they don't work too well either. But they're all notes from the very scale, over the very chord in question!

One of the main things a bassist does, in general terms, is to outline the prevalent chord. To do that, the chordtones get played, and they sound more convincing when they happen on particuar points in a bar. Namely the 1st and 3rd beats, speaking broadly. When you did what I suggested in para.2, neither of those were met.

Yes, you could just play up and down a scale - in fact, were it the pentatonic minor scale, it would work quite well. As proven by many a beginner guiarist/bassist. That's an improvement note-choice-wise, on the whole scale, as it omits two 'iffy' notes.

However, to play something which fits the sequence better, and sounds more musical, playing 1 on 1 is a good (often expected) place to start. So, if you played in a scalar manner (going sequentially up the scale, note by note), starting each bar on the appropriate scale note, it will start to sound like you know what's going on. On an Em bar, play E F♯ G A, on a D7 bar, play D E F♯ G, on an Am bar play A B C D, etc. Note that all the notes are still from that Em scale. And E natural minor will be fine.

I'm keeping it simple so far, so using notes 1 3 5 poss. 3 again), instead is another way. They fit perfectly, as they outline the notes from the triad of each chord.

There are going to be many more options than merely playing straight 4 in the bar, but the above tenets will still be the bare bones of what gets played. So when you said you do use the Em scale notes they fit, I say yes - and no. Those notes are the ones most likely to fit and sound o.k. Why wouldn't they? They all belong to the key of E minor - tha's why we put them all in the same scale - but rest assured that other notes may fit better. As you rightly say, A minor doesn't have F♯. (It actually can have, but that's for another day!). But since the piece is in key Em, the notes from that key will always work best.

A bit like talking to someone in English, and suddenly throwing in a Swahili word - often going to throw the listener!

Of course there will be times when a note that's out of key will work best, but at grade IV level, I wouldn't be too bothered about that yet. As an aside, have a look at RGT bass grades - they have a different take on things, which may shine some lights on queries you may have.