Hi Debra,
Since you also have a small pack of B's I have to ask... do they ever peform Basenji Operas?
My older male and female will "sing" back and forth at each other, usually trying to resolve a dispute such as who gets the best seat on the couch. It can go on for up to five minutes, but they will not do it while a family member is in the room. Their songs consist of something like the "ba" part of a baroo, but drawn out for ten seconds or so for each "verse".
I've been trying to capture a recording of one of their operas, but as soon as I get near them they stop mid-performance!