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In regards to dialogue editing and noise removal, I've read John Purcell's book and it is absolutely brilliant, however it is written under the assumption that someone else will be mixing the material after it is edited. In this case I'll be doing the editing and mixing.

I'm wondering how much noise reduction I should use on dialogue once it is edited. There is a high pitched hum throughout the dialogue in a certain scene. It has different pitches depending on the shot and occasionally completely different tonal characteristics. Now as advised by Purcell, I have edited the dialogue by finding room tone in the handles of the audio files to ensure that I have enough clean room tone to fill in the gaps between dialogue.

Now that I'm down to the mixing stage, do I want to noise process the whole lot to remove this pitched tone and replace it with more suitable, subtle room tone? Or do I keep the room tone as is?

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Here's what I'd do, as a dialogue editor at heart myself:

  • cut the scene across a set of DX A-F tracks or more, if needed, but I shoot for using only A-F

  • split the 'angles' out according to the noise/hum characteristic this may be something Purcell's book didn't address, and is also why I consider his book to be a great introduction to dialogue editorial, but by no means a complete bible - the meat and potatoes of successful dialogue editorial is that most issues are all about situational context, strategy, and sideways/adaptive/intuitive thinking. In a normal scenario you might split out the OMF onto DX tracks by character or shot angle, but intuitively the first way I would approach the scene you desribe when I roll over it in the OMF is splitting out the angles according to the noise problem.

  • backfill accordingly, overlapping noise is OK the idea here is to smooth everything over gently, especially if the noise bumps in timbre between angles (aside from the harmonic issue). If this means that sometimes the backfill on two different tracks is running simultaneously at times, then there's nothing wrong with that - it's all about making a smooth-playing dialogue track. Editing like this may take a little more time, but it pays off at the stage because when the reel is tossed up, even with the noise issues, it 'plays' and allows the mixer to focus on specific noise issues like the hum without running the risk of disrupting the flow (or having the find/create the flow!)

  • Notch EQ on the DX track-level << this is particularly if you're doing your own predub, they way I like to predub my dialogue, otherwise a mixer will likely do this instead or have their own method. This is where "write to all enabled" is a GODSEND. basically, you can select the entire , say, 20 second area of dialogue from fade in to fade out where a certain hum or buzz is, bypass the automation and enable loop playback so you can spend time finding and notching out the noise problem. Then, before enabling automation, hit the "Write to all enabled" command, and you're pasted that EQ notch (even if you did multiple ones inside the plugin) across the ENTIRE selection. This is where having done your split outs according to the noise/hum problem makes this method so easy, because you're allowing a dedicated EQ to each isolated noise problem/track instead of dancing between noise types sharing the same track.


After all of that, I recommend trying some real time broadband noise suppression techniques using multiband processors. Cedar DNS is the king but often prohibitively expensive, but the Waves C4 works exceeding well, and for it's price as a single plugin it's a total steal (I've since been on some major dub stages where I've seen the C4 being used in this way too, so I'm definitely not the only one who is using this method nor the only one having success with it).

This is the rundown on it with a before/after sample:

http://www.stavrosound.com/blog/wordpress/2011/07/dialogue-clean-out-the-noise/

Check out the screenshot of the session too - that sample had harmonic buzz problems from lights in the room and the RED, but the way those edits are laid out are basically a visual representation of what I said above. SO that should hopefully provide some context for what I said and provide you some tangible results. Good luck!

P.S. I'm not against FFT-based processors like RX or XNoise, they definitely have a place in dialogue cleanup and can be valuable. In my opinion though, I don't prefer them at all as a first line of defense. I prefer to evaluate my dialogue through a proper predub sidechain with something like a C4, and only then determine if I need to apply some FFT noise suppression as a roll over a line of dialogue. Sometimes it's quite magical when gently 'lifting' a teeny bit of noise with something like a C4 can do to your dialogue.

  • That's a great summary. fantastic. – Kurt Human Mar 1 '13 at 10:14
  • Excellent write up and very good advice! – Arnoud Traa Mar 1 '13 at 12:07
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typically the reason that noise reduction is left until mixing is because once you have context of everything else that's happening you can gauge exactly how little noise reduction you can get away with.

The reason you want to do as little noise reduction as possible is because all noise reduction removes some part of the tone and timbre of the voices onscreen in addition to the noise that goes away. The more of the original recording that makes it through the more you'll have to work with in the realms of EQ and compression.

Alternatively, sometimes you really DO have to go nuts with NR to clean something out, and the surrounding music and effects may effectively mask some of the NR artifacts that would otherwise stick out if the track were soloed.

its all about context.

In your situation I'd evaluate the changing tonalities in the context of everything else in the mix, and then treat the elements until those high pitched things are sitting just outside of audibility.

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Probably this question will be answered once you know what you want to do with the scene! And since you're mixing it, you should an idea where the scene is going in terms of feel (for example full/empty, real/dreamy, wide/hyperfocussed, just sound fx/also music and so on). Maybe you don't know about the music, that can be trouble. Too much noise in your dialogue can really destroy an emotional moment in a scene with music, for example. So there's no simple answer I'm afraid. You'll have to try which treatment will work for the scene.

On the technical side: those changing whines can really be a pain in the ass. But if you're lucky the scene takes place in an office, where whining sounds do happen (computers? printer? lamp buzz? You can mask your dialogue-whith those sounds... Hope that helps...

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The Noise-removal make it sound little bit hollow. To fill out the gaps you could try use a "pink noise generator" with a "noise gate" side chained to your dialog track.

You might ask why adding noise when you just removed it. I believe that the pink noise is more comfortable then internal machine noise or room noise. For this project I´d set the pink noise generator at -56dB.

I did a export of my version where I added a "limiter", took a way some dB:s at 700Hz and 1000Hz. I also used highs and lows from V1 (for the atmosphere) panned with binaural spherical pan at size 6.5 meters.

My one is louder though I mixed the dialog at -23 LUFS according to TV-standard EBU r128. You can download it here: https://www.dropbox.com/s/hlxaywzr9vvhsae/V6.wav?dl=0

My mix is pretty dense. I guess its a matter of taste after all.

Best Regards Martin Sjölander

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Thanks for the quick responses. Ive uploaded 2 versions of the mix to mediafire and would be greta if someone could take a listen and give me some advice. V1 is without Noise removal and V@ is with.

http://www.mediafire.com/?xydv7axb0t259xd

as the scene does take place in an office, my gut feeling is stay as far away from noise removal as possible and just embrace the natural room tone of the dialogue.

thanks again!

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