Used carelessly, these kinds of processors can introduce zingy, warbling artifacts that can be worse than the noise itself. But with a careful touch, this class of plugins can bring down an incredible amount of noise without a trace. Although they’re capable of removing huge gobs of noise in a single pass, many users find they’re most transparent when applied less drastically across two or more stages of more subtle noise reduction.
Out of the three programs I tested intensively this month, iZotope RX2 proved to be the one to beat. Without touching a single variable, RX2’s De-Noise function was able to scrub away astonishing amounts of broadband noise with minimal artifacts. For even better results on tricky material, it offers a host of tweakable parameters, but more often than not, they were barely necessary. At only $300 for a whole suite of restoration plugins, it is a no-brainer.
In second place was Wave Arts’ MR Noise, which was just as effective and transparent as RX2 after a bit of futzing with the sidechain EQ. At only $250 for the whole suite, it’s a solid buy.
Waves’ Z-Noise found itself in a respectable 3rd place. It’s capable of getting many jobs done, but not quite at the scale or with the ease-of-use found in the best noise reducers.
Even after sampling the noise profile and going through the extra step of setting the threshold and NR range before hearing any improvement, Z-Noise’s default settings just aren’t what they should be. You’ve got to play with the attack and release times to even approach the kind of results that RX2 and MR Noise deliver before any futzing. Even once it was set to the best of its ability, I found that Z-Noise couldn’t scrub out quite as much interference as was possible with comparable settings in RX2 or Mr Noise.
At $500 and up for the single plugin and $1,100 for the entire Restoration package (Native), it’s hard to recommend Z-Noise with so many great alternatives out there – except as a welcome value-add to a larger bundle of some of the better-realized Waves plugs.
Hums, Clicks, Crackles, Pops and Plosives
These kinds of noise-reducers can do a great job of reducing broadband noise, but they’re practically useless for reducing intermittent noises like clicks, crackles, pops, plosives and clipping. They can also be pretty rotten at reducing the high-level hum caused by ground loops, amplifiers and electric guitars, which often occupy the same frequency ranges as the program material you’re looking to preserve.
Waves’ X-Click and X-Crackle did a commendable job of taming many high-level transient sound-bursts, as did the de-noising and de-crackling modules from iZotope and Wave Arts. Each of their packages also included a hum-busting processor that essentially notches out a set of frequencies, such as 60Hz and all the harmonics above it, perfect for taking care of ground noise.
(For those of you who only need a hum reducer, the most cost-effective option is probably McDSP’s NF575 hum filter for only $130 Native, and as a welcome addition to their bundles. But similar results can be had with any bank of simple notch filters and little bit of setup.)
Until very recently, pops and plosives were usually best taken care of by hand, through the judicious use of high-pass filters and gain rides on tiny snippets of audio. To this day, the biggest problem automated processors have with these low low-frequency aberrations is not with eliminating them but with identifying them in the first place. Specialized tools are now available from the cutting-edge developers at Cedar and even as part of Wave Arts’ specialized noise reducer package, Dialog, that help clean up these problem areas without effecting the surrounding audio.
Izotope takes a unique and especially transparent tool for removing plosives and intermittent interferences in RX2: next-generation Spectral Analysis. So far, they’re the only company I know of that has included this type of feature in a DAW-based noise-reduction plugin.
Today’s spectral analyzers are a whole new class of multi-function audio tools. They do more than just provide visual feedback of the frequency distribution, essentially allowing the user to “unmix” audio tracks by zooming in and removing tiny portions of the source sound.
One of the earliest and most powerful consumer-facing spectral analyzers has been Sony’s SpectraLayers, which takes a Photoshop-like approach to audio.
With SpectraLayers, you can zero in on a single sound out of many embedded in one file (say, an ambulance siren among chirping birds, a honking horn in the middle of a stretch of dialog, or an out-of-tune horn in a music mix) and extract it to its own “layer,” separate from the main mix. From here, you can effect it in isolation, extract it from the surrounding the material, or remove it completely.
SpectraLayers is powerful, but it works only as a standalone app. RX2’s spectral functionality might not be quite as exhaustive as that of SpectraLayers, but it’s supremely user-friendly, and comes embedded in a DAW-based plugin and offers great new tricks for routine noise reduction.
Encounter a pop or plosive? Reach out, grab just the frequencies that are affected and mute them. Need to delete an intermittent word, click, squeak or breath but don’t have any room tone? RX2’s spectral “replace” function erases the offending sound and automatically fills it in with surrounding tone. No copying or pasting needed.
For the first time, these new types of processors allow us to effectively remove discrete noises that occur concurrently with our desired audio: phones ringing, sirens blaring, birds tweeting, horns honking.
These are tools that would have seemed like audio science fiction a generation ago. Although no noise reducer may be able to fix every problem, the processors around today have transformed once-impossible jobs into everyday realities.