I've been searching Google about this a lot but couldn't find a solution for it. For example, in the solo part of "Nothing Else Matters" where does the A# come from? I can understand why, for example, C# can be used in a E minor, even though E minor doesn't have that note, due to D Major having it in chord progression. Can someone please enlighten me about this. Thanks.

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    Tunes are not written with regard to music theory. Music theory is - theory. Not a law, or even a set of rules which must be followed. Please don't try to analyse everything that happens in music using the 'theory' as a guideline. Although a 'guideline' is actually all it is.
    – Tim
    Jan 24 '17 at 19:08
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    Ok thanks. So basically, as long as it sounds 'good' to one's ear, I can use every combination, right?
    – Berk
    Jan 24 '17 at 19:12
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    it's the old adage - if it sounds good, it probably - is! Regardless of whether theory says so.
    – Tim
    Jan 24 '17 at 20:27

A♯ in e-minor is just a blue note. These are found all over rock music. Yes, it does not really fit in the key, classically speaking, but that can be used as a deliberate effect – it's a dissonance used to convey a somewhat painful emotion, or... whatever, you must know for yourself how you perceive it.

As Tim says, in principle you can use any note in any key. Just you should have a feeling what effect it incurs for the listener. Choosing only notes from the key's default scale makes sure that nothing will sound too jarring, but often it also won't be particularly interesting.


I suggest looking into 'non chord tones.' This will give you some music theory terminology which can be used to describe and label notes that don't 'fit' a given chord. The artful use of non chord tones adds expression to melodies. You find them in practically every style. Pop, classical, rock, etc.


If a chord in a measure (bar) does not have any notes that are less than four semitones (frets on one string) away from the melody notes then it often can be played without clashing with the melody. It may not make any harmonic sense but it will work.

Say you are playing in the key of D and you play a bar that consists of the melody notes E B D. You could play an Em7 (E-G-B-D) or an E7 (E-G#-B-D) chord in that bar. Why? Because in order for the G# in the E7 to clash with melody, the melody would have to have an F, F#, G, A, or Bb in it.

I used the length of a bar for simplicity but this applies to any duration of the melody notes and the chord.

Note that one way you can use a clashing note is if you put an octave or more of distance between the notes. C next to D is a clash but C above D is a dominant seventh.

  • While it's not entirely unsubstantiated, I find that “less than four semitones” rule quite questionable. G♯ - D is a tritone, that's arguably more dissonant than a minor third (which has less than four semitones). Same for that A♯ in the OP's question, which is basically used because it clashes. And, even a major second (in an add9 chord), or even a minor second (in a maj7 chord) can be used without “clashing”. Jan 25 '17 at 23:21
  • If you add an octave to a "clashing" note, then it's more than 4 semitones.
    – empty
    Jan 26 '17 at 0:43
  • I have jazz tastes and so don't find that tritones "clash", that is, are displeasing to the ear. YMMV. Music is a constant dance between assonance and dissonance.
    – empty
    Jan 26 '17 at 0:47

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