‘Whisper Not’ is in the key of D minor, the natural, relative minor to F major. We have seen a couple of songs in “harmonic minor” keys (Link). In this case the 7th degree of the scale is not raised so the piece takes on a smoother texture (the sharp 7 drives harder to the tonic). In fact the piece begins on a minor VII chord (softer yet) setting up a temporary IV – II – V – I sequence to G minor. The sequence is then repeated to the D minor tonic.
The ‘B’ section reflects the same chord changes as the ‘A’ section but adds some rhythmic contrast with nice little punch chords.
Example 1
To get started improvising on ‘Whisper Not’ you might like to try something like Example 2 in the left hand.
Example 2
Example 3 has a couple of tone groups to try. The first seems to work over the first three or four bars the second over the next four of five.