Rob Bee from B Double E holding a card that says 'Izotope RX9'.

Izotope RX9 For Voiceovers – Do You Need It?

It’s very hard these days to look on a forum and not see someone posting about Izotope’s RX suite of plugins – currently on the 9th generation. Many people have offered forth the opinion that it’s an essential purchase for voice overs. So here’s my contribution to the discussion. And I’m going to disagree with many people, and at the same time agree with them.


What is RX9?

So the immediate question is what is this thing that causes all the fuss? RX9 is a suite of plugins, and a standalone editor, that offer some very powerful processing options for audio restoration and polishing.

screenshot of Izotope RX9 restoration tool.

It includes things like:

  • De-clipper for if your recordings have peaked above 0dB (technically impossible, but you know what I mean), a music re-balancer for tweaking a mix to make the vocals stand out a bit more (or the drums, etc.)
  • De-reverb plugin to improve the clarity of your audio a bit and many other modules to improve the quality of a bad recording.
  • The standalone editor also includes a lot of processes that you’d expect in a regular editor like some EQ, signal generators, normalisation, batch processing and loudness controls.

It comes in 3 different price levels – essential, standard and pro. The prices of these reflect the number of plugins and processes you get. There’s a comparison chart here. It is very good at what it does, and I use it fairly regularly.


Why shouldn’t voiceovers use RX9?

All of this sounds amazing. Some of those modules look like they’re directed specifically at voice overs – mouth de-click, de-plosive, breath control, voice de-noise and de-ess for example. So why shouldn’t a voiceover buy RX9? It’s because of what it is. It’s an audio restoration suite.

As voice artists we’re doing all our recording in a controlled environment where we don’t have noise interruptions (most of the time!) and we control the environment so it isn’t reverberant. We don’t need audio restoration. Or we shouldn’t.

I see too many voiceovers who have a noise reduction process as a part of their post-production schedule for every job and it makes me cross. If you need to use noise reduction on every job you do you really need to improve your recording environment. If you don’t need to run a noise reduction process, then don’t. Noise reduction processes – RX9 included – run the risk of damaging your audio, taking bits out that are part of the program, or leaving artefacts in the audio.

I cannot state enough that voiceovers shouldn’t need most of what RX9 has to offer.

I use RX9 fairly regularly because I do get given some audio restoration jobs from clients. The tools it presents for that purpose are very powerful, but they have limitations. As a voiceover, you should never hit those limitations, but you can still get into situations where you’re over-processing and doing more harm than good.


Why should Voiceovers use RX9?

Because it’s very good!

Those aforementioned processes in particular can be helpful in creating some highly polished great quality audio. But over-use it and it can just create different problems.


How should voice overs use RX9?

With care!

There are some RX9 modules that are worth their weight in gold.

Mouth de-clicker

The best example of this would be the mouth de-click. If you buy the Elements edition of RX9 you get a de-click, and it is possible to successfully get rid of mouth clicks with this, depending on exactly how your clicks sound.

Screenshot of Izotope RX9 mouth de-clock tool.

The regular de-clicker isn’t looking for mouth clicks, the algorithms are looking for electrical clicks, dropped samples and the like. If you upgrade to the standard version of RX9 you get a dedicated mouth de-clicker, and if you’re doing long-form audio this can save you hours of time and your sanity.

Small pause here just to say that mouth clicks are one of those things that voiceovers often get paranoid about, and worry unduly that they’re too clicky. They can spend hours getting rid of clicks that simply aren’t there. I think this may be a topic for a different blog, but for now please know that no one hears your clicks as much as you do.

The default setting of the mouth de-click seems to clear up most clicks from most people. But I’d suggest that backing it off a little from default can do as good a job and have less risk of taking out bits it shouldn’t. I usually back the sensitivity down to 3 from the default 4, and am more often than not happy with that.

So what happens if you overuse the mouth de-click?

Some people have reported that it can leave artefacts – a sort of metallic edge to the sound, but it’s more likely to misidentify some word endings as clicks. Words that end with a K sound that have been pronounced softly do sometimes lose the K. Less often it may be a T or P that gets chopped.

Let’s think about another couple of the modules while we’re here.

Voice de-noise

The voice de-noise does what it says it does. If you’ve recorded something in a noisy environment it identifies the voice and attenuates everything else. It can run in adaptive mode, so if the noise changes it can still be lowered.

Screenshot of Izotope RX9 voice de-noise tool.

It’s a very powerful plugin. For voiceovers it can be used to lower your noise floor. Overused it will definitely leave artefacts in your audio.

So how should it be used?

For voiceovers I’ve only ever used it on audiobooks I’m mastering for ACX. Sometimes ACX books need a high degree of compression to meet the RMS specs, this raises the noise floor above normal, and possibly above ACX’s requirements. My first port of call would be to add an expander into the signal chain as this will lower the noise floor in the gaps and keep the noise floor low – no I wouldn’t use a noise gate. There is the possibility though that you may still be able to hear the noise floor below the read. This is where the voice de-noise could be useful. I’d use it to further reduce the noise floor by 2 or 3dB in the gaps to ensure it’s low enough to pass ACX, and this will also remove some of the noise from below the read, but shouldn’t be enough to result in artefacts. Gentle is the key. It’s a belt-and-braces approach with the expander doing the heavy lifting.

Breath control

There may be another blog in de-breathing a read, but for now all you’re getting is this bit!

Screenshot of Izotope RX9 breath control tool.

We all worry about how best to remove breaths from a read – or indeed if we should. RX9 offers the breath control module to aid us in our strife! All well and good, but the best way to de-breath is still manually. Totally removing breaths with this kind of process can leave a read sounding lumpy – our breaths are very much a part of the rhythm of our read, and disturb the rhythm, and you run the risk of sounding like the dreaded ‘we’re getting Joyce from reception to do our advert’.

So is this a useful module?

It can be. I’m guessing that it’s really aimed at singers, or maybe lip-syncing/ADR where the words need to be in a fixed point in time. But for other voicing applications, it is possible to simply reduce the level of the breaths rather than remove them completely, so that’s what I’d advise. But even this comes with a big warning. It’s really easy to over-apply the breath control module. And if you do you’ll end up chopping out bits of words -particularly words that begin or end with F or TH sounds.


And the rest

There are many other useful modules in RX9. So here are my bits of general guidance as to how to get the best out of it.

As I’ve said already, use it sparingly and conservatively. The most important thing to do is preserve the quality of your audio. Don’t use it to the point where you’re doing damage. If you’re running the breath control or the mouth de-click and you’re getting rid of 80% of your problem before you notice undesirable effects you’ll still have saved yourself a ton of time. You’ll need to manually fix the other 20%, but your audio will still be pristine.

Don’t forget the help section

At the top right hand corner of each module is a question mark. Click it and it’ll take you straight to the right page of the user manual where you’ll find an explanation of what the process does and a description of every button and slider.

In conclusion

Here is the most important bit. We all run into an audio issue from time to time and need to use pieces of software like this. But you shouldn’t rely on RX9 to achieve professional quality audio.

It’s always better to solve a problem at the source.

RX9 is a tool best used subtly even though it can be used to the extreme when needed. You can use duct tape to fix a leaky pipe, but it’s better if the pipe doesn’t leak in the first place.


If you need more help and guidance with RX9 (or other software) then get in touch and we can arrange some 1-2-1 tuition. If you need help improving either the quality of your studio or the quality of your audio so you don’t need to buy RX9, I’d be very happy to help with that too!

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