All of mine would baroo, but they were pretty stingy about it. I find Basenjis tend to vocalize when they are impatient or frustrated about something. One of my girls would vocalize if I "threatened" her by holding my hands over her head. My first boy would sometimes baroo, but was a wonderful howler. I got him started by making noises through an empty paper towel roll cardboard. He started howling and once he began he would keep it up for awhile. This became a behavior that was "on cue". He would howl if I sang his "baroo" song to him, and his other cue to howl was saying "You're nothing but a dog, and that's all you'll ever be". That would get him going, and I could even hold him upside down while he continued to howl. Too funny!
My current boy usually vocalizes if we are late with his meal or if we delay going out after loading his roller ball. He gets impatient waiting for us to leave, so he can have his treat. He will also join in if I start howling like a wolf.
Three of mine would give a fox bark, usually if startled. My current boy will give a bark at a stranger. My old girl would only put her fur up and "huff". All have had an impressive "snark" if disturbed when comfortable.