When realizing figured bass, passing notes in the bass are analyzed quite thoroughly in literature (e.g. The Art of Accompaniment from a Thorough Bass). However, I cannot find any information or rules on improvising passing notes in the higher registers. However, I do see it happen. For example, here in this realization of measure 7 of SWV 289:
To me, it seems like it is desirable to have those transition notes since they connect upper voice of the BC. However, here it does double the soprano which I thought was undesirable from the bass.
I have the following questions about these notes:
- Is the realization above even any good?
- Is there literature (perhaps only practical) about these notes?
- Are there rules they should obey?
To give some more examples:
This is a really frivolous realization with many notes added. In the following, you have a D# added in the second measure of the alto. Otherwise there would be a consecutive unison with the bass. So I might infer from this a rule saying you can add a half step down between two notes.