Friendly Assault bombs

When the DLC came out the assassin cloak was changed so that only opponents hear the hum. Could it similarly be changed that you don't hear friendly bombs. I am (fairly) sure that I have heard them. It's confusing, either that or I've been lucky enough to run past some without the owners noticing.

I'm (pretty) sure the bombs have a slight color. That way, you can tell if it's safe.

The same could be said about the assassins, the trouble is you can't always see them