All the basenjis I have ever had "boof" when on alert. They all seem to understand that it means something like "heads up, guys, possible trouble". Don made that sound once, playing with the 5 we had then, and they were not amused, they looked at him like he had 2 heads and didn't respond at all the way they did when a basenji said 'boof'. They would play with him mimicking all other basenji noises, but 'boof' was sacred.
Athena is just telling anyone around to be on alert! If you ever watch any meerkat shows, the watchers make a sound that produces the same results, everyone stops whatever they are doing and all look around to locate the source of the alert.
LOL, a couple of weeks ago Cara began boofing for no apparent reason. MOST the time it's a dog outside and she wants dogs (oh and thunder) to know only she gets to make noise. It took me a couple of days to pinpoint it. I had started playing a new game, Gardens of Time, and when you change scenes, it sounds like a bark (My child insists it's a wooshing sound of the time machine but obviously Cara and I both disagree). LOL she has finally stopped though.