Friday, July 11, 2008

Noise Reduction shoot out - Sound Forge, iZotope, Audacity, Audition, Waves, and doin it by hand!

So, this is going to be a longer post...

We're going to compare 6 different methods of noise reduction.

I get a lot of questions about cleaning up audio after recording, hums, clicks, pops, line noise, neighbors, fridge, etc. A lot of people are still trying to gate or EQ this stuff out, and those methods don't work particularly well for voice over, especially dry auditions.

Gating will turn off the audio signal when you're not speaking, which gives you perfect silence, but when you start speaking again the noise is back too. This can be VERY unnatural depending on the noise.EQ can work, but usually to the detriment of the entire piece of audio, as you are carving out chunks of the frequency spectrum. Those chunks start carving into your voice as well. Sort of like destroying the town to save the town...

Ideally you'd just want to record clean in the first place, but sometimes you just can't help but knock something out and hope you can clean it up after the fact.Noise Reduction plugins to the rescue!To test, I set up my Solaris to records in "Figure 8" mode (so the front and back of the mic are recording equally), set one side up for me, and put the other side of the mic right up against my bathroom door with the fan running.

This is a worse case scenario for voice over, as fans tend to generate noise that slices right through the middle of the human voice's spectrum. That means that as you remove fan noise, you're likely carving out a chunk of the voice as well. A less extreme version of this would be a fridge kicking on or the AC running.

All of these plugins (and doing it by hand) work on the same general principal, point out what undesirable noise looks like, and try to get rid of only that noise. [Check out the Audacity Tutorial for Noise Reduction in practice - Ed.]

I attacked the samples pretty aggressively with each method. For the test, the main idea was to all but eliminate the background noise, even if it damaged the voice. Real world, you would probably want to leave a little more noise to prevent damaging the recording.

So first up, here's the unaltered file:

Sony Sound Forge NR plugin:

iZotope RX De-Noiser:

Audacity NR plugin:

Adobe Audition NR Plugin:

Doin it by hand with Phase Inverse:

Waves Restoration X-Noise:

Again, this is most certainly a worst case scenario when it comes to noise reduction, and hopefully you don't encounter this much noise on a regular basis. I find the results interesting listening back. There are two methods up here which are essentially free, and the most expensive plugin comes in a pack which runs about $1000.

So what do YOU think? Are there other plugins that I'm missing?


  1. From what I heard he two biggest contenders for eliminating a majority of the noise was the sound forge plug-in and the phase inverse. the rest sounded like it was recorded slightl;y underwater, and one even sounded kinda like a toilet flushing at the end (teehee)...

    I won't be spending another 300 bucks on a new audio pack (my back pocket is still aching from the Cubase "upgarde" to Studio4), and I for the life of me cannot figure out the whole phase inverse deal. How do you do that? Could it be as simple as inversing the entire clip?

  2. Audacity was my first pick, followed closely by Sound Forge. I am assuming that you used the same amount of processing for each one of the filters. Generally with the Sony noise reduction there is a point. Start at -13db and then ease up -12, -11, -10 until it sounds really good and easing up doens't make it sound any better.

    Unfortunately X-Noise for some reason wouldn't play for me, so I can't judge it but I had used that with some success a few years back working on a Mac Protools setup. My Friend Matt Donner, who has written several books on Pro Tools swears by X noise.

    I suppose the big surprise for me was Audacity actually sounding quite good.

    I would also like to see what Bias Noise reduction would have done compared to these others. Their product is Sound Soap and Sound Soap Pro and run around $125 and $500 respectfully.

  3. LOL Jody!
    Nope, no flushing thanks... It's all the same file.

    I was a big X-Noise fan too, but I was also very surprised by the other methods. The newest "beta" of Audacity has some KILLER plug ins.

    It was hard to scientifically match the reduction amounts on each plugin. I mention it's not quite scientific, but the idea was to hit the file aggressively to the point of full on noise removal. Essentially a WORST case scenario, even to the detriment of the source recording.

    Sound Forge's advantage for me, was it seemed to have the most precise attack, release, and shelfs, but I agree that the actual filtering seemed to be the cleanest on Audacity.

    Inverse worked awesome on the noise at the end, but was REALLY hard to line up samples around my speech. Did the least actual damage to my recording though.

  4. i'm a starting musician and the first time we tried to record some demos with my friend, we used such a creepy mic that no software could fight all those hisses and clicks. BTW, we used adobe audition 1.5 and once i tried to reduce the noise level the sound became "watery". later we just took an SM57 from a friend and that time i wasn't bothered at all.)) i do not say the quality was good. i know nothing about how to perform mastering and stuff, but that time it was ok for our first demos. so, thanks for the info. i'll try it next time i get to recording.;)

  5. The SM57 has been a studio staple for decades. It's probably the most versatile dynamic you can get, and the only mic I like better is the SM56.

    Noise reduction is tricky stuff, and you really have to keep your ears on for it. You might only be able to drop your noise floor a couple dB, but every little bit helps.

  6. Thank you. This was very useful. Any more recent updates for this?

    I would also like to know a little bit more about the the settings (parameters) for each.

  7. Man, been a long time since I looked this article up. Haven't really played with any new plugins for a while. I don't really know what new NR plugins there are out there.

    The trickiest thing about setting up a quick comparison was that each plugin had to be used in a different DAW environment, and they each control reduction in different ways.

    At the time I felt the fairest way to compare would be to use what ever settings would reduce the noise floor by a similar amount, with attack and release settings (if you could even change them) as close as I could get them across the different plugins.

  8. I was surprised by just how good Sound Forge (and how poorly Adobe Audition) performed in this test. (I couldn't get the X-Noise sample to perform, either).

    I have used Audacity a lot; and Audition a little, as radio-related work requires it. But still unsure how they should be tweaked.

    Thanks again.