Well, so far, just sitting around the house or out on the deck, listening to the stereo and playing along, I can hear what I'm doing just fine. The stereo is at a volume that allows normal conversation, so not terribly loud.
Now, my wife said she can't hear what I'm playing, so maybe it's not much good for being heard by others acoustically. But then again, she can't pick out the bass line in something like Rush's Spirit of Radio, so I'm not sure she's the best judge.
Anyway, at least I don't annoy her with my playing along...

I have NO idea what to do with those skinny stringed things... I'm just a bass player...