Noise Reduction - tips and tricks

[Guy Rowland]

The whole field of noise reduction has changed dramatically over the past few years with the introduction of machine-learning algorithms that can routinely perform miracles.

I've posted elsewhere about my experiences with Hush Pro, which I demoed to professional sound recordists earlier this year. Without exception, their jaws dropped to the floor on a demo of a personal lav mic where the dialogue was drowned out by seawash. Hush Pro was essentially perfect, separating the voice and seawash into separate files with no discernable quality degradation at all. It really did feel miraculous.

I recently tried it on a job even though the main rig is Windows and this is Mac-only. I figured I could render files on the Macbook, and transfer back. This particular job was recorded in a kitchen - plenty of room noise, sizzling pans and various cookery noises that I needed to separate into voice and effects files. To my unhappy astonishment, Hush Pro didn't detect any of the cookery noises at all, even the sizzling, and kept it all as dialogue (it did a pretty good job on the room reverb though). It really hit home to me just how variable these tools can be - the same plugin that produces perfect results on one clip can not even touch another. At the moment it feels like the more plugins you have the better your odds.

In terms of more forensic work, one trick I've used possibly more than any other over the years is the most basic - copy and paste. So often the best and cleanest solution to a specific nasty problem is to copy a part of the frequency band next to the problem area, and paste it over the thing you don't want, a la photoshop. Any editor with a spectrograh view can do this - I use RX.

I haven't yet found any plugin for a job like mouth delick or deplosive that is 100% safe to use in auto-mode - even set conservatively they can falsely detect real speech frequencies and eliminate, or it can miss stuff. RX's tools here are very good but not infallible, so I just do it when I need it (and I often just choose the rough frequency area with the problem, rather then do it for an entire broadband file). For deplosive, I sometimes do a different very lo-tech trick - especially for female voices I just use a 48db high pass filter. I look on the spectragram for the lowest genuine speech frequency I can see and set the HPF to right below this. It's amazing how well it can work - in these cases I have been able to blat an entire batch and forget it.

[Lawrence]

The whole field of noise reduction has changed dramatically over the past few years with the introduction of machine-learning algorithms that can routinely perform miracles.

I've posted elsewhere about my experiences with Hush Pro, which I demoed to professional sound recordists earlier this year. Without exception, their jaws dropped to the floor on a demo of a personal lav mic where the dialogue was drowned out by seawash. Hush Pro was essentially perfect, separating the voice and seawash into separate files with no discernable quality degradation at all. It really did feel miraculous.

I recently tried it on a job even though the main rig is Windows and this is Mac-only. I figured I could render files on the Macbook, and transfer back. This particular job was recorded in a kitchen - plenty of room noise, sizzling pans and various cookery noises that I needed to separate into voice and effects files. To my unhappy astonishment, Hush Pro didn't detect any of the cookery noises at all, even the sizzling, and kept it all as dialogue (it did a pretty good job on the room reverb though). It really hit home to me just how variable these tools can be - the same plugin that produces perfect results on one clip can not even touch another. At the moment it feels like the more plugins you have the better your odds.

In terms of more forensic work, one trick I've used possibly more than any other over the years is the most basic - copy and paste. So often the best and cleanest solution to a specific nasty problem is to copy a part of the frequency band next to the problem area, and paste it over the thing you don't want, a la photoshop. Any editor with a spectrograh view can do this - I use RX.

I haven't yet found any plugin for a job like mouth delick or deplosive that is 100% safe to use in auto-mode - even set conservatively they can falsely detect real speech frequencies and eliminate, or it can miss stuff. RX's tools here are very good but not infallible, so I just do it when I need it (and I often just choose the rough frequency area with the problem, rather then do it for an entire broadband file). For deplosive, I sometimes do a different very lo-tech trick - especially for female voices I just use a 48db high pass filter. I look on the spectragram for the lowest genuine speech frequency I can see and set the HPF to right below this. It's amazing how well it can work - in these cases I have been able to blat an entire batch and forget it.

Interesting-I wonder how Clarity VX would have done on your kitchen noise?

[Guy Rowland]

Interesting-I wonder how Clarity VX would have done on your kitchen noise?

The best of the lot as it happens. It's not perfect, but it gets me 80-90% of the way there with one of the algorithms.

And this just goes to show. I was ready to give up on Vx after RX11 improved on Dialogue Isolate, but it still absolutely has a place. Everything is case-by-case.

[Lawrence]

Interesting-I wonder how Clarity VX would have done on your kitchen noise?

The best of the lot as it happens. It's not perfect, but it gets me 80-90% of the way there with one of the algorithms.

And this just goes to show. I was ready to give up on Vx after RX11 improved on Dialogue Isolate, but it still absolutely has a place. Everything is case-by-case.

You bought the pro, right? Big difference?

[Guy Rowland]

You bought the pro, right? Big difference?

Not a big difference - you can finesse a little bit, but it's fairly marginal. But what Pro gives that IS invaluable for me is the ability to remove voice, not just boost it. This current job needs the noise and voice elements separated into two, and you can't do that with the base plugin. However if you don't need that functionality, the base version is 90% of the Pro one. There MAY be some specific cases where Pro would benefit.

[Lawrence]

You bought the pro, right? Big difference?

Not a big difference - you can finesse a little bit, but it's fairly marginal. But what Pro gives that IS invaluable for me is the ability to remove voice, not just boost it. This current job needs the noise and voice elements separated into two, and you can't do that with the base plugin. However if you don't need that functionality, the base version is 90% of the Pro one. There MAY be some specific cases where Pro would benefit.

...and it does it do that separation very well?

[Guy Rowland]

...and it does it do that separation very well?

At its best - yes. You usually get it a bit artefacty or pumpy, but it can be very clean in a best case.

The whole experience has been fascinating. When I set up a demo on that exterior beach stuff, Vx was really weak and I'd stopped really thinking about it. I started to wonder if I'd been too hasty using it on a production a couple of years ago, but this has reminded me it can work very well.

At the moment I'm not sure what to expect from any of them. You just try them and pick the one that works best today. In terms of tips and tricks, that's the main takeaway for this cohort.

[Lawrence]

I’ve been surprised at how well Clarity works for recording acoustic guitar and voice. I don’t have a lot of isolation and I’ve been able to remove a lot of room noise, etc. There are artifacts, but there’s usually a pretty good compromise between less artifacts and just a tiny bit of noise.