Reducing Room Tone in Dialogue

Greetings,

I'm presently in post on a short film. There seems to be audible room tone in a dialogue sequence in the -30 to -35 decibel range. The noise comes across as an audible hiss. I've used the dehisser, noise reduction, and dehummer on Fairlight, and tried lowering the volume while using keyframes to raise the volume of the voices to little avail. The dialogue was recorded with a Rode Boom on a Tascam dR40x.

I would appreciate any info on how I may be able to improve audio using DR16 studio.

Thanks.

A.B.

Can you supply an example? If you don't want to make it public you're welcome to PM me a link.

If I can't suggest anything with what you have, I have a bunch of audio restoration and repair tools and would be happy for process the files for this project for you for free.

Can you supply an example? If you don't want to make it public you're welcome to PM me a link.

If I can't suggest anything with what you have, I have a bunch of audio restoration and repair tools and would be happy for process the files for this project for you for free.

First, thanks for the reply.

I am going to try one more thing and see if I can proceed from there. Basically, lowering entire clips and using keyframes to raise the dialogue, then see if an effect or fiddling with the dynamics and gates can reduce the room tone hiss and not result in voices sounding wonky.

If that doesn't work, I'll be in touch.

Use a gate, adjusting parameters for natural sound. Then go back and add a slight amount of real room tone on a second track (complete silence is unnatural).

Run a short section of the clip through software that will give you a Spectrogram, so you can see where the offending sound actually is.

Use a gate, adjusting parameters for natural sound. Then go back and add a slight amount of real room tone on a second track (complete silence is unnatural).

I tried using a gate and while the audible hiss is reduced in the parts of the clip before and after the dialogue, we can still hear it when the actor speaks. I have already added a track for room tone to cover the gaps in dialogue but feel the room tone hiss is still too much in the audible range. As mentioned, the room tone of both (the dialogue clip and room tone clip) are in the -30 to -35 range. I am trying to achieve a -40 to -45, which will still be audible and not total silence, which is indeed unnatural.

Thanks for the reply.

Run a short section of the clip through software that will give you a Spectrogram, so you can see where the offending sound actually is.

Thanks, will look into that!

I tried using a gate and while the audible hiss is reduced in the parts of the clip before and after the dialogue, we can still hear it when the actor speaks.

That is pretty much the definition of what a noise gate does.

You need to use something like iZotope Advanced to clean the dialogue first. This is what happens when you have either high levels of noise on set, or a mic not close enough to the actors, or actors who don't speak loud enough, or noisy mics, or noisy preamps, or some combination of all of these. My advice would be to clean the dialogue carefully with iZotope standalone outside Resolve, then bring the cleaned tracks back in. I would not try to run it as a plug-in.

You have to be very careful at adding controlled roomtone back in. The danger is that if you have the roomtone up continuously, you can wind up with double roomtone when the actor speaks. The best book on the subject of dialogue editing is John Purcell's Dialogue Editing for Motion Pictures, and he goes into great detail on how best to achieve this.

https://www.amazon.com/Dialogue-Editing ... 0415828171

It's fair to say that dialogue editing and cleaning up and matching dialogue is every bit as difficult as color correction or mixing music or picture editing or any other part of post. It's very, very complex, and a lot of it hinges on starting with the best possible results on set.

There is no easy answer. Gates sound terrible. All of the automated one-click solutions available now have audible artifacts. Choosing the right tool and knowing how to adjust it to suit is learned from experience.

Do you only have the built in Fairlight effects to choose from? If it's just normal roomtone/HVAC noise the denoiser can work OK. But the key to this and any other noise reduction is just that - Reduction. You're trying to lessen the noise not eliminate it. Usually starting with EQ is advisable. Also starting with a decent signal to noise ratio is essential. If the subject is too off-mic or the noise is too loud then you're fighting a losing battle from the start. Whatever you do compare the before and after. To make sure you're actually improving it.

Thanks for all the responses. This truly is a learning experience for me and I appreciate all the responses.

I think the culprit was the lack of a preamp. We used a Rode NTG4 and Tascam DR40x.

Now the question is how to reduce the hiss, which I believe I have mistaken for room tone, from the recordings.

I'm including an example of the hiss hoping someone can guide me further in the right direction. This is an audio file (.wav) of a couple of takes from a scene of my short film, PURGATORY. Since I cannot attach the file (too large, apparently), I will provide a google drive link (hope that's kosher):

https://drive.google.com/file/d/1WbslEAbUHKkzZBR-1oRax71E1Q6tZiJA/view?usp=sharing

Again, thanks for all the help. You guys rock!

-A.B.

PS. Here's a teaser for the project. The audio is still a little wonky. I'm doing my best but may need to seek professional help soon if I cannot fix the quality of the audio:

https://drive.google.com/file/d/1z7hLmLu0LieKsn0dqTBtX1KuG9VsyrfW/view?usp=sharing

Yep, you guys could have done a better job recording the audio. Also, watch out with balance between the music and the dialogues! In the teaser, the music is way too loud in proportion with the dialogues. That said, take a look at iZotope's "RX7". I recommend it for cleaning up your dialogs.

For reference here is a spectral view of you clip, and then one of my sample clips. I used Audacity (free) to generate it, as that's the only thing I have access to at work.

All that extra light blue up and down the frequency range is what you are hearing, and its not something you want. Also all the redish/pink between the dialogue is noise as well.

Yours

yours.jpg (925.7 KiB) Viewed 5932 times

Mine

mine.jpg (960.86 KiB) Viewed 5932 times

Having listened to the clip once, it sounds like the mic was really far away from the talent, and then a lot of gain was applied. How was this rigged up?

I pulled 29db at 565Hz with a Q of 26, and 22db at 896Hz with a Q of 26.
Also lost everything below 100Hz and above 4K.
That cleans it up to very tolerable levels.

For reference here is a spectral view of you clip, and then one of my sample clips. I used Audacity (free) to generate it, as that's the only thing I have access to at work.

All that extra light blue up and down the frequency range is what you are hearing, and its not something you want. Also all the redish/pink between the dialogue is noise as well.

Yours

yours.jpg

Mine

mine.jpg

Having listened to the clip once, it sounds like the mic was really far away from the talent, and then a lot of gain was applied. How was this rigged up?

We used a RODE shotgun NGT4 MIC on a boom and a Tascam DR40x. The mic was directly overhead from the talent, a couple of feet away at most. I do believe the lack of a preamp is the reason for the hiss or contributed greatly to it. Several reviews of the unit recommend their application when using the xlr jacks.

Thanks for the spectral views. It gives us a good idea just how badly we/I screwed up. Lol.

Cheers.

I pulled 29db at 565Hz with a Q of 26, and 22db at 896Hz with a Q of 26.
Also lost everything below 100Hz and above 4K.
That cleans it up to very tolerable levels.

Using DR16 Studio Fairlight? That is all I have at my disposal. If it is possible to do so, can you fill me in on how you did it? Hope that's not asking too much. My goal is to clean the audio to the degree it does not sound totally amateurish.

Thanks!

Yep, you guys could have done a better job recording the audio. Also, watch out with balance between the music and the dialogues! In the teaser, the music is way too loud in proportion with the dialogues. That said, take a look at iZotope's "RX7". I recommend it for cleaning up your dialogs.

Indeed. Our sound guy did not show up on our single day of indoor production. We did the best we could with what we had, though. Thanks for the heads up on the music/dialogue ratio. I'll reduce the music just a little bit. I think I've raised the dialogue as high as I can without making the faults of the recording glaringly apparent. Also thanks for recommending iZotope's "RX7." It's a bit out of my budget right now, but I'll keep it in mind for future productions.

Cheers.

Actually, I did that EQ thing on my audio software.
With DR16 you can just add the Noise Reduction FairlightFX and instantly get a passably clean dialog track.
In fact, I'm surprised at how effective it is. There's a checkbox to hear the noise only so you can hear what's being removed.

Okay, this is worse than I was expecting. The microphone was way too far away from the talent.

That hardest problem to fix is the reverb. Lowering reverb brings in unpleasant artifacts.

There are large volume variations, which will need compression. Unfortunately, in this case compression is going to bring out the problems more, so the best you can expect to achieve is a compromise.

I've done a basic pass with a few tools, but I'd need to put more time into it to get it any better. I'm working on my laptop with small external speakers in an untreated room, so not ideal.

To do it properly I need to do it in my studio.

https://drive.google.com/open?id=1OYGKy ... suJP-yTYNu

You mentioned adding gain after the event. Hopefully you have the original, unaltered files.

If you want to supply me with all the files to work on, it would help if you can supply the originals without any processing.

By the way, not sure how capable Fairlight's side chaining is, but it's possible to use a couple of expander gates with side chaining to get some degree of controlled room tone back in.

Sounds like you don't have a lot of audio experience, so I can help you with that too. If not in Fairlight, then I can do it in other software for you.

By the way, not sure how capable Fairlight's side chaining is, but it's possible to use a couple of expander gates with side chaining to get some degree of controlled room tone back in.

Sounds like you don't have a lot of audio experience, so I can help you with that too. If not in Fairlight, then I can do it in other software for you.

Hey Mike,

I'll send you a pm soon. Got caught up at work.

-A.B.

That sounds like heavy HVAC/room noise to me not preamp noise. But I'm listening on an iPad not at my studio.

I've never used an NTG4 but the NTG3 is surprisingly good. However I don't think a shotgun is the best choice for that type of environment. Short hyper cardioid usually works out better.

Also consider the environment. Quiet down the room as much as you can. And think of acoustics just as you would think of lighting. Adapt to the location as much as possible. Treat a live reverberant room with some sort of absorption any way you can. I realize you had an absent sound mixer so this is mostly for future advice.

Suggest reviewing this: http://www.rode.com/blog/all/a-guide-to ... -equipment

Also note need to turn off HVAC, refrigerators, dishwashers, computers with cooling fans, etc. when capturing sound indoors.

Make sure someone is monitoring through good headphones that block a lot of the surrounding sound - if it is noisy in the headphones, don't bother recording until that gets fixed.

That sounds like heavy HVAC/room noise to me not preamp noise. But I'm listening on an iPad not at my studio.

I've never used an NTG4 but the NTG3 is surprisingly good. However I don't think a shotgun is the best choice for that type of environment. Short hyper cardioid usually works out better.

Also consider the environment. Quiet down the room as much as you can. And think of acoustics just as you would think of lighting. Adapt to the location as much as possible. Treat a live reverberant room with some sort of absorption any way you can. I realize you had an absent sound mixer so this is mostly for future advice.

Thanks for the tips.

Yes, I think I was totally mistaken blaming it on preamp noise. It definitely sounds more like loud HVAC.

Suggest reviewing this: http://www.rode.com/blog/all/a-guide-to ... -equipment

Also note need to turn off HVAC, refrigerators, dishwashers, computers with cooling fans, etc. when capturing sound indoors.

Make sure someone is monitoring through good headphones that block a lot of the surrounding sound - if it is noisy in the headphones, don't bother recording until that gets fixed.

Thanks for the links and the tips. We were running and gunning and only had access to the location for a day. We did our best. Next time, we'll take into consideration turning off all the electrical appliances. If memory serves, the fridge and central a/c noise were prominent.

Okay, this is worse than I was expecting. The microphone was way too far away from the talent.

That is a huge problem that is nearly impossible to solve with processing. I've often said, "it's better to have a $100 mic in the right position than a $2000 mic in the wrong position."

For a lot of reasons, fast-paced TV productions often place wireless lavs on all the actors in addition to using a boom, because that way they always have a clean-sounding track they can go to. You would be surprised how many films and shows use this technique these days; it's not unusual for a dozen or more actors be on wireless mics in scenes.

One crappy Rode mic 12 feet away from the actors in bad acoustics is not going to yield good results. At some point, you either have to reshoot, or re-record all the dialogue (ADR), or clean it as best you can and live with mediocre sound. And learn a valuable lesson for next time.

That is a huge problem that is nearly impossible to solve with processing. I've often said, "it's better to have a $100 mic in the right position than a $2000 mic in the wrong position."

This cannot be emphasized enough.

Mixing and booming can only be learned from experience. Unfortunately there aren't enough people getting proper training. And the gear is a lot more obtainable now than it used to be. I constantly receive terrible tracks from people using quality gear. It's very disheartening.

By the way I wouldn't try any of the so-called de-reverb plugins on this. Most of them sound atrocious and even worse when you're off-mic.

I would still advise what I mentioned above. Starting with EQ then trying the Fairlight denoiser to gently knock down some of the noise. Avoid heavy compression. Hopefully the scene is supposed to be a big space so the sound fits the picture!

Okay, this is worse than I was expecting. The microphone was way too far away from the talent.

That is a huge problem that is nearly impossible to solve with processing. I've often said, "it's better to have a $100 mic in the right position than a $2000 mic in the wrong position."

For a lot of reasons, fast-paced TV productions often place wireless lavs on all the actors in addition to using a boom, because that way they always have a clean-sounding track they can go to. You would be surprised how many films and shows use this technique these days; it's not unusual for a dozen or more actors be on wireless mics in scenes.

One crappy Rode mic 12 feet away from the actors in bad acoustics is not going to yield good results. At some point, you either have to reshoot, or re-record all the dialogue (ADR), or clean it as best you can and live with mediocre sound. And learn a valuable lesson for next time.

Lesson learned. Thanks for the info and suggestions. Your knowledge on the subject has been invaluable to a novice filmmaker. Thanks again for taking the time to respond.

That is a huge problem that is nearly impossible to solve with processing. I've often said, "it's better to have a $100 mic in the right position than a $2000 mic in the wrong position."

This cannot be emphasized enough.

Mixing and booming can only be learned from experience. Unfortunately there aren't enough people getting proper training. And the gear is a lot more obtainable now than it used to be. I constantly receive terrible tracks from people using quality gear. It's very disheartening.

By the way I wouldn't try any of the so-called de-reverb plugins on this. Most of them sound atrocious and even worse when you're off-mic.

I would still advise what I mentioned above. Starting with EQ then trying the Fairlight denoiser to gently knock down some of the noise. Avoid heavy compression. Hopefully the scene is supposed to be a big space so the sound fits the picture!

The scene takes place in a loft in downtown Denver. While the loft was large, we only used the living room portion. I think a minor reduction in the noise is all that is really needed. Thanks for the suggestions. You guys have been awesome.

Did anyone (e.g., Mike Warren) fix this file for you? I was able to remove the worst of the noise very easily with Izotope RX; there were a few good seconds of room tone to sample from. Izotope's "Dialogue Isolate" tool helped remove a little reverb but introduced some artifacts when I gave it a quick try, but I didn't (and don't) have time to fine-tune it. The harder problem is that compressing the dialogue and using makeup gain brings up the noise floor underneath, because (as everyone pointed out) the mics were too far from the actors.

Did anyone (e.g., Mike Warren) fix this file for you? I was able to remove the worst of the noise very easily with Izotope RX; there were a few good seconds of room tone to sample from. Izotope's "Dialogue Isolate" tool helped remove a little reverb but introduced some artifacts when I gave it a quick try, but I didn't (and don't) have time to fine-tune it. The harder problem is that compressing the dialogue and using makeup gain brings up the noise floor underneath, because (as everyone pointed out) the mics were too far from the actors.

Yes, we do have someone working on it. Thanks for taking time to work on the file, though. If you don't mind, can you post or send me the results? This is definitely a learning experience for me and I'd like to listen to different takes on fix attempts.

Thanks.

Izotope's "Dialogue Isolate" tool helped remove a little reverb but introduced some artifacts when I gave it a quick try, but I didn't (and don't) have time to fine-tune it.

I just upgraded from Standard (bought on sale) to Advanced and some of the Advanced tools are surprisingly good. I had some audio where I tried a bunch of other RX tools in varying combinations and had something usable, and when I upgraded, I was stepping through the various Dialogue ... tools (the main reason for the upgrades) and Dialogue Isolate clobbered the noise and most of the reverb out of the box. It's not a magic wand and didn't do as well on other audio, but I was shocked that a single tool was able to do what it did on several test cases.

So it pays to try the entire RX toolbox and sometimes you get a one-tool wonder result. (In general, a combination of careful steps works best, but sometimes one tool just approaches it with a different algorithm that simply matches your problem better.)

I got RX-8 Elements on sale for $30 and used it right off the bat to eliminate some click-ish sounds from Slack that someone left running on their laptop during an interview. And then erased a jet overhead in another interview. (It had doppler shift, so wasn't a constant tone, and painting it out did what I needed.)

Then upgraded to Standard, also on sale. And finally have upgraded to Advanced which is definitely a big step up price-wise. (Though also including some plugins that are magical under the right circumstances.)