It used to be that filtering of sound was only available through the use of an equalizer - emphasize certain frequencies and cut others. A minimal solution that seldom worked. For years this was all that was available unless someone actually worked with each "frame" of sound and hand deleted the frequencies of the "noise."
Nowadays, there are inexpensive (and expensive) software programs that can delete any particular noise or sound. Hum or cam noise would be a good example. If any particular "noise" can be isolated, then it can be removed from a scene or from a whole movie. But you must think on this process and what it does. For instance, I really wanted to get rid of a baby crying from a concert I recorded. I was able to isolate it when there was no music playing, but applying this noise deletion to a real shot cut out every frequency that the cry had. In other words, almost all high frequency sound was lost.
Now if you take this scenario to the afore-mentioned example, the "noise" is voice. Cutting out voice sounds does just that - it cuts out all voice frequencies more or less. So it won't work.
Now if you have an old scratchy record and want to re-record it digitally without the scratch or pop, it works.