‘PRAM in D’ (PD 21-07-15) demonstrates how the A minor riff material (for example) can be a springboard for your own improvisations and compositions.
You can make your variations different by:
Here is the riff performance. (There is no written music.)
Taking a bird’s-eye view of the structure, or form, of a piece, is an important element of playing by ear– and from memory.
Here’s a digital work-station screen-shot of the PRAM in D MIDI.
Listen to the riff and track your position in the screen-shot.
Identify these elements.
– Two false starts and all the way up;
– Two false starts and all the way down;
– All the way up and all the way down.
– All the way up and all the way down;
– Four-phrase ending.
Here's a fourth improvised variation on-page, which uses a mix of the riff patterns in both A and D minors.
No written-out music! Here's a screen shot to help.
Getting this by ear would be a benchmark achievement.