A song full of 4ths, 6ths, 7ths, 9ths, Total Eclipse of the Heart - Jim Steinman sung by Bonnie Tyler

It is written on one of the most difficult keys on our planet.


The key or scale of B flat minor. Very few composers including classical ones dare use this scale full of black notes. It sounds fantastic.


Since A minor has all keys white or natural, it is evident that transposing one semitone up most piano keys will be black.


But it's much better to think of it not as a transposed A minor but as a B flat minor.
The B flat minor scale is:


B C D E F G A B where
B is flat,
D is flat
E is flat
G is flat
A is flat
so only C and F is natural or white.


The most extraordinary chords begin as soon as the intro begins.


Bass is B and the piano plays F D
Bass keeps B and piano plays E C ie a 4th and a 9th


(Remember to add the flats when you play otherwise it sounds nonsense)


The vocal creates most fantastic prepared 9ths, 7ths, 4ths etc.


A truly masterpiece of music or engineering.


The bass code [Bach] goes like this:


B
B 4 9
A
A 4 9
C
B
C
B
modulation to E major ie all F,G,C,D sharp
E Turn around
A7 Bright eyes (this A C# E G# ie A major 3rd major 7th)
E
A7 (the major 7th interval ie A to G sharp is prepared by the melody).
then modulation to A flat major
A And I
F7 Need you now tonight
D7 ...
E45 resolved to E ...
A Than e-ver, notes sung are G G A ie prepared 7th (major seventh)





Reference:
Bach Bass Rules - Bach, Niedt, PDF


See also: Harmony - Piston