Note: these exercises are specifically aimed at guitarists/bassists but can be adapted for use with other instruments:
Exercise: choose a position on the fingerboard: covering four frets (plus the possibility of a half step stretch on either side). It should be possible to play the chromatic scale from there (check). Listen to the following piano chords. For each chord, determine which notes sound ‘good’ against the chord. Listen to each of the 12 notes in the chromatic scale: the best notes are ‘target’ notes (notes to be targetted in the creation of lines/phrases): we can stick around on these notes! The other notes are ‘approach’ notes (or passing notes) – whose purpose is to get us to the target notes: we don’t stick around on them. Without getting too theoretical at this stage – recognising the chord type by sound or what scale(s) can be played over it – play through all of the notes and learn to distinguish by ear. The theory can come later on!
Later on…see if you can work out what to call each chord you hear as above. If it doesn’t come to you immediately as an intuitive response then work it out: by identifying which of the 12 notes of the chromatic scale sound like chord tones. Note: here we will distinguish between chord tones and tensions – extra notes added to add spice and colour. It is good if you ca mentally separate the notes you hear: singing the notes is better: organise them into an arpeggio from bottom to top. Within the position chosen, find these notes and upon that basis, work out a name: a type of chord and indeed root note. Clue: these are all 7th chords though some have a 9th added; and so they are based upon tertian harmonic principles of chords based on stacked 3rds. Of course, the voicing may be less straightforwards and so you are faced with inverions and compound intervals. Try to spot the core triad upon which the chord is based: it will be either major, minor, augmented or diminished. That should help to identify the root, although in the first exercise above, the root is already established as C. Once the root is established, it becomes possible to codify the notes into a chord spelling which will identify a chord type. Bingo!
Another exercise: hear the chord and try to sing a short phrase over it using a bunch of agreeable notes (although it does not have to consist of target notes exclusively). Then play the phrase on the fingerboard in your chosen position.
Finally – see if you can come up with a scale (no not the chromatic scale) with between 5 – 9 notes that work with the chord. Whilst you may use your ear given the above, you may already know some scale types that work with the chord type identified.