20.34A practical clue
If a chord sounds like a dominant 7 but its root isn't 5 of the main key, ask:
What chord would this dominant naturally resolve to?
That may reveal a secondary dominant.
Example:
In C, hear D7.
D7 wants G.
So likely:
V7/V
If a chord sounds like a dominant 7 but its root isn't 5 of the main key, ask:
What chord would this dominant naturally resolve to?
That may reveal a secondary dominant.
Example:
In C, hear D7.
D7 wants G.
So likely:
V7/V