In box: Getting Rid of Background Sound

Sound Advice

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How to get rid of Background Sound?

I am a director/filmmaker with about 3 exterior shots in my indie film. My film editor tells me we need to do the dialogue over with the actors, because of a generator and a jackhammer in the background. Is there an easy way to take the background sounds out in post editing?

If it were simply a hum or a buzz, that could be fixed in post-production. But since it is a generator and jackhammer, you will have to do ADR. It may cost you money to pay the actors to come back, but ADR is much easier than trying to fix the poorly recorded audio. It will be less time consuming as well. So choose where you want to spend your money… paying your editor to work long hours so he can fix audio that probably won’t come our right anyway, or paying actors to come back for a day and re-record.

Do not take audio lightly. It is the most important part of video. You get more information from the audio than you do from the visuals. So if your audio isn’t perfect, there is no way your video can be perfect. And trust me, your viewer will know when the audio sucks.

In my opinion, this situation could have been avoidable. Who was in charge of recording audio? He or she should have heard at least the jackhammer in the background through headphones. You don’t even need headphones to hear a jackhammer…

Rob is right, Sound is extremely important. If you must record on location where you have a lot of background noise then plan ahead. One option is to go on location a week before and shoot the location with video and audio, then bring your actors to a chroma key studio and shoot the scene. You can add the background sound you want by using Foley sound. This will cost a little more but will produce a much better film. 2nd option: fire your sound guy. 3rd option: spend thousands on post -production.

If the generator audio is consistent like that of the all-too-familiar AC hum, then, if it’s not the exact frequency as the vocals, it’s possible that frequency 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 intrusion 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.

All the above is correct. I had a similar problem on a film with a rug cleaning service. I was staring down the ADR barrel, but did as Earl suggested and was able to EQ the sound of the cleaners out and still maintain believable nat sound.

You may be able bring the jackhammer sound down to an acceptable level depending on your editing/audio software. But if you have mono/dialog going over the jackhammer, I hope you recorded clean nat sound before or after it kicked in ’cause you’ll need it when you have to lay in the ADR track. NewBirthProductions is also dead on, both your audio guy/gal and you should have caught that in the field. You can shoot on-location and get excellent sound, but as Rob mentioned do not take your audio lightly. Bad audio will kill a flick faster than a lame plot. Please let us know how you solve this.

Can’t speak to the jackhammer problem, (can you live with it)? But the generator noise might be able to be filtered out using Sony’s SoundForge or Adobe’s Audition or SoundBooth. None of these will be perfect (or as good as ADR) but it might be good enough – Also depends on whether you have a couple of seconds of the generator hum by itself (to be used in the noise reduction filters).

One last bit of advice: if you can’t mask the jackhammer, make it a part of your production. Off-screen sound is more annoying when you never see a visual of that noise. If your audience can clearly understand the dialog, and the jackhammer seems like it’s just background sound, try throwing in a short clip of a street scene that has a jackhammer in use, to let the audience identify the noise. It might not work, if the jackhammer so badly overrides your dialog, but it just might be an easy fix, too.
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