"ringing" after using RX2 to denoise?

[hoodleehoo]

Forgive me if I'm in the wrong forum, but I just got RX2 to clean up audio for a film I'm helping with. It does a great job, but the director listened to one of the cleaned up tracks and said he hears a ring after anyone talks. I don't know how to describe it but it's like a resonance that continues for less than a second after any kind of sound. It took me a bit to hear what he was talking about so I don't think it's terribly noticable. Plus, he had it turned up so loud that what little hiss there was was extremely noticable. Granted, the dialogue recorded isn't very loud.

Does anyone know what this ringing is? Is it from having too much smoothing?

[DaVogi]

could also be a room resonance... you could lower the parts after someone talks and fill it with room-tone.

[hoodleehoo]

Originally Posted by DaVogi

could also be a room resonance... you could lower the parts after someone talks and fill it with room-tone.

It's so quick that I don't think it would be possible without really messing up the audio. The ring isn't in the original audio, just when I clean it up. I used a lot of smoothing, could that cause it?

[bkuijt]

The Hum Removal filters in RX can cause heavy ringing when you engage 'linear-phase filters' and apply a lot of harmonics or apply multiple passes of it.
But actually it is most obvious in front of the audio, try some static piano chords for example.

[Whitecat]

It may have to do with the smoothing, but it could be simply too much noise reduction.

With dialogue, I always start by leaving the smoothing slider in the default spot and only increasing it if I get artefacts after noise reduction (and then only increasing it as much as necessary).

You may want to try a) using fewer db's of NR and b) doing multiple passes of NR at lighter settings each.

Beyond that an expander plus some ambience might be the next thing on the list to try.

[Alexey Lukin]

Originally Posted by hoodleehoo

Does anyone know what this ringing is? Is it from having too much smoothing?

Try different algorithms (A/B/C/D). They produce different results.
'A' (the default one) can leave tails of weakly suppressed noise after speech utterances. I'm not sure if they can be described as ringing.
Other algorithms should not have this effect.

P.S. You should attach a before/after sample for better diagnosis.

[charles maynes]

less is more- and many times multiple passes will work better than one pass through the plugin.

[Jfriah]

I find it personally amusing that the director was commenting on the sound of the processed file!


I like his ears! (or, her ears...sorry. how poor of me)

My GUESS is that it is exposing the remaining verb of the location which used to be hiding under the noise.

Have you tried offline processing it (much longer) to hear the difference?

Jeff

[Brian B]

My guess is that what you're hearing are pre-echos caused by intense filtering, similar to those produced by sharp hum removals. The de-noiser is essentially a several-thousand band eq, and these are artifacts of the process.

As suggested above, try processing the material with less aggressive reduction, but do a few passes. This will probably give better results.

[Thomas W. Bethe]

Originally Posted by charles maynes

less is more- and many times multiple passes will work better than one pass through the plugin.

RX is one of the best Noise reduction softwares around but you do have to learn to use it and as Charles has said less is more in a lot of cases. Best of luck!

[jamesp]

Some de-noising software has a decay control that controls how quickly the filters start working after the signal has gone below the threshold. Is there such a thing in RX2? Can you control the FFT size? A smaller FFT size will result in fewer bands of noise reduction but possibly a faster response.

And, as others have said, don't go for too much noise reduction in one pass. Some people recommend no more than 6dB at a time but I tend to use 10-12dB per pass. It also sounds better if you leave a little noise in there - totally silent backgrounds are very unnatural.

James.

[Alexey Lukin]

If you have RX Advanced, you can control FFT size in the advanced tab.
However even RX standard has algorithms 'C' and 'D' that adaptively choose the best FFT size for every portion of the signal (to minimize ringing near transients and improve reduction depth on steady signals).

[cananball]

Had this recently but could only hear the resonance if you stopped playback in the middle of a processed clip. Sounded like pulling a finger out of a neck of a bottle.

I have not tried different alogarithms but would definately recommend multiple light passes as opposed to a single heavy pass. I typically reduce about 2-3 db 2 or 3 times per clip with no artifacts.

Sent from my DROIDX using Gearslutz.com App

[hoodleehoo]

Thanks guys. I guess I'll try multiple passes, I didn't know that would make a difference!

Any other tips for denoising using RX2 are welcomed. I'm an excellent student!

[Jfriah]

Personally, I find better results when I can do a separate pass of heavier Tonal if that's part of what I need to get rid of, and very light (2-4) broadband and then go broadband adjustment / recapture after.

Jeff

[seanmccoy]

I do find that I need to turn smoothing down or completely off when doing medium to heavy NR on production dialogue. The smoothing tail at the end of each isolated line seems to focus attention on the process. As mentioned, a little expansion like the C1 can also help mask this. More smoothing works well when doing NR on continuous sources like hissy music tracks.

[hoodleehoo]

Hmmm, I know the 4 algorithms are different, but I've been using D mostly. Doesn't D use the others as well? If D has a problem, is there any use trying the other three?

[RScott]

For the kind of work I do, simple dialog and music to pix, I find the mix context to be very helpful for settting Noise Reduction levels due to this low-level artifacting. With more in the mix, you can afford to bump up the noise reduction a hair more.

Sure, if the director has the track soloed and cranked up, he will hear the resonances, but have him listen in context, preferably with an A/B between the original, your noise reduced track, and maybe even an alternate with less noise reduction on.

Noise Reduction is a give and take. You take the lower noise by giving sonic integrity and clarity. There is usually a happy medium where the tool gives you a better end product than the original, but still, you aren't going to turn it into a clean production track.

[Alexey Lukin]

Originally Posted by hoodleehoo

If D has a problem, is there any use trying the other three?

Yes.