How music works? Πως λειτουργεί η μουσική;

We can find or play the melody (which is the most difficult part to compose anyway) by ear.


But what about for example the left hand while playing the piano, the bass, the chords or harmony?


It is easy.
All needed to remember is the series note after note.
That is: do mi sol si re fa la do mi sol si re fa la do mi ...
Or in different notation:
c e g b d f a c e g b d f a c e ....


Then a particular bass can have its companion notes or chord derived by usually the closest to it in the series.


For example.


Let it be - Beatles


Lyrics: when I find ... Bass is C
Chord is C E G


Old and Wise - Alan Parsons Projest
Lyrics: As Far... Bass is A
Chord is A C E
then bass is G
Chord is G B E (the further E is chosen by composer)
then bass is F
Chord is F A C E
then bass is E
Chord is E G B D
Then bass is F
Chord is F A C E
Then bass is E
Chord or Harmony is E G B D
Then bass is D
Harmony is D F A C
Then bass is E
Harmony E G B D
Then bass is A
Harmony is A #C E


More rare but very beautiful is the case when notes further from the series are used for example
First chord of Just Hold Me - Maria Mena
Bass is A:
Harmony is A C E B (a major 9th chord since A B is an interval or musical distance of major 9th).


One more thing. One needs to also know the particular musical scale that is used. For example if it is E minor (all white notes exept #F) so as to know which sharp or flats to play.


For example: Hey you - Pink Floyd
Key is E minor
First bass is E, bass code is E9
First chord as derived is E G B F (remember F is sharp)
Easy


And another hint:
As Bach explains [Bach, Niedt] when left hand goes left right hand must move to the right. This avoids consecutive 5ths which sound bad and makes possible at the same time the least change which sounds great.
Example: Let it be - Beatles


C bass and C E G
G bass and B D G (instead of G B D)
A bass and A C E
F bass and F A C E (creating prepared F maj 7th)
F bass and F A C D (F maj 6th)


Another possible example, subtle chords played by Hammond organ, Leslie rotating reflector speaker on:
Goodnight Moon - Shivaree
https://m.youtube.com/watch?v=tCXeYq6KYZc


See also:


Bach bass rules - Bach, Niedt


Harmony - Piston