Videomaker – Learn video production and editing, camera reviews › Forums › Technique › Sound › How to get rid of background sound?? › If the generator frequency
If the generator frequency is consistent like that of the all-too-familiar AC hum, then it is quite possible that consistent frequency (if it is not the exact same as the vocals) can be neutralized in a good audio editing program. Possibly the same for the jackhammer, though I am sure its frequency levels will be over a range rather than a consistent level – more challenging, but probably not impossible.
At the least you could likely minimize the intrustion via audio editing software and playing around with the frequencies. At worst, you will discover the limits of this approach quickly (should be rather obvious after one test) and move on to bringing the actors in for ADR.