ReaFIR Madness – The Hidden Noise Reduction Tool in Reaper

Reaper audio recording software is awesome, and is what I recommend to everyone.  I use it every day.  And I also seem to learn something new about it every day.  It has an incredible noise reduction tool built right in that I just discovered recently.

ReaFir Effect in Reaper
ReaFir Effect in Reaper

The reason I didn’t know about it sooner is primarily due to the fact that reducing recorded noise is not its only or primary function.  It just happens to do it REALLY well, and non-destructively (if that’s not a word already, I hereby create it).  The tool is called ReaFIR.  I know!  Who’d have thought to look for noise reduction editing chops under a moniker like that?

Review of What Noise Reduction Does

First though, let’s do a quick review of what noise reduction does for us in the world of recording.  There is almost always a bit of background noise in recorded audio.  It is especially noticeable in recordings of just one thing, like a single voice. 

The noise usually comes from a combination of stuff happening in the space/room where the recording takes place, and the electronics of the microphone and other gear involved.  Recordings sound much better if you can reduce the noise, and that is what noise reduction tools are designed to do.

The typical method is to use an effect in an audio editor called “Noise Reduction.” See my article How To Get Rid Of Background Noise In Audacity for how that normally works.

But since the noise and the voice are both together in the same recording, it isn’t a perfect process.  What noise reduction tools try to do is filter and removing as much noise as it can without also removing too much of the voice. 

In order to do this, the software has to know what noise looks like so it can separate it from the signal (voice).  So you have to highlight a section of the recording where there is ONLY noise, and no voice, and feed that sample to the noise reduction tool.  Once it has the noise profile, it can do its thing.

My favorite recording program, Reaper, is a digital audio workstation (DAW), which is a fancy way of saying full-featured multi-track recording program. For more information on why I love Reaper so much, see my article, Why Reaper Rocks As A DAW.

But for some reason, Reaper doesn’t have an effect called “Noise Reduction.” So how do you reduce noise in Reaper?

Enter ReaFIR

Reaper names its effect plugins by using “Rea” as a prefix (for Reaper), and then the name of the function after it.  So ReaFIR means Reaper FIR.  So what does FIR mean?  It stands for Finite Impulse Response.  If you would really like to geek out on what it really means, including all the scary math involved, you can read about it at the Finite Impulse Response Wikipedia page.  But the simpler definition for ReaFIR itself from the Reaper manual is:

ReaFIR is a EQ and dynamics plug-in that includes an FFT spectrum analysis window. Amongst other things it can be used as a precision EQ, a gate, a fast attack/release precision compressor, a noise reduction tool.

Obviously it is that last thing we’re interested in.  In the video below, I walk you through how to use ReaFIR to reduce the hiss noise that happened when I recorded a short voice over.  BTW, this video was recorded several years ago (why it says from the “upcoming” course). That course, The Newbies Guide To Audio Recording Awesomeness – Part 2, has now been around since 2012 and had been updated may times since.

How Does It Work?

FX button in Reaper
FX button in Reaper

So see it in action in the video above.  But here is is a written summary of how it works.  Once you have recorded some audio onto a track, click the FX button in the track control panel.  Then select VST: ReaFIR from the Cockos collection of FX plug-ins.

Next, go ahead and click the “OK” button and then close the ReaFIR window by clicking on the red X in the upper right corner.

Now just highlight/select a section of the voice-over audio that has no voice actually saying anything.  In other words, pick a small area that was only noise.

Then click on the Toggle Repeat button (down by the Play and Stop buttons).  This is important because it will prevent any of the actual voice signal being played when sampling the noise for ReaFIR. With that area still highlighted, click on the FX button again to open the ReaFIR window.

Add FX to a track in Reaper
Add FX to a track in Reaper

In the Mode window of the ReaFIR tool, select Subtract, and put a tick into the Automatically build noise profile box.  Now hit the Space bar on your keyboard (which will play the audio, which is just the noise at this point).  You’ll hear it for a second and then it will be gone.  That’s ReaFIR getting rid of the noise.  Now hit the Space bar again to stop playback.

The next part is very important!  Uncheck the box that says Automatically build noise profile.  Otherwise ReaFIR will try to grab your voice and anything else on the track, and treat it as noise.  Once you’ve done that, go ahead and close the ReaFIR window.  Now all you have to do is click on the Toggle Repeat button again to turn it off, and listen to the entire track.

Voila!  The noise is gone and only the voice remains.  Pretty darned cool huh?  And I think the result is better than a lot of tools dedicated to removing noise.  I didn’t hear much, if any, of the weirdness that sometimes happens after noise reduction. 

The audio takes on a kind of swirly, under-water-y artifact sometimes.  But I didn’t hear that in this example.  However, there noise we got rid of was a low-level and consistent hiss type of noise. 

The louder the noise and the more varied the noise (if it contains lots of frequencies and intermittent clicks, pops, etc.), the more likely you are to have that swirly artifact left over after noise reduction.

So now you know about the secret noise reduction tool at your disposal if you use Reaper.  Use it wisely.

Free videos from “The Newbies Guide to Audio Recording Awesomeness”

These video tutorials show you step-by-step, in plain language how to record multi-track audio in Audacity AND Reaper software.

29 comments on “ReaFIR Madness – The Hidden Noise Reduction Tool in Reaper”

  1. Awesome! Works very well. I was doing a album video-review and I kind of forgot how reducing noise with Reaper worked. So I quickly searched for some guide on the internet and stumbled upon this guide. the instructions in the video were very easy to follow and I learned something new as well, I think I never used ReaFir. So thanks a lot!

  2. It didn’t work for me. FX didn’t turn red on one try. And on another try, although it turned green, the noise was still there.

    1. Heather. Things can turn out weird if you don’t do things in just the right order. I actually just messed it up the other day. First, removed the effect from the track. Then – and here’s where I messed up – make sure what BEFORE you do anything, highlight a section with ONLY noise AND hit the Toggle Repeat button (or hit the “R” key on your keyboard). This ensures that when you load ReaFir again, there is no chance anything other than noise can play. Now load up ReaFir again. Choose “Subtract” from the dropdown menu, and put a check mark in the “Automatically build noise profile” box. Then hit the spacebar on your keyboard to play the audio, which will just loop the selection of only noise. Once that plays for a few seconds, hit the spacebar again to stop playback. Then – and this is critical – take the checkmark out of the “Automatically build noise profile” box. That should do the trick. The only potential problem at that point would be if the noise you wanted to remove was too lour or too similar to the “actual” audio your recorded onto the track. I hope that helps!


  3. Once you get used to Reaper it is a great DAW. This is a great tip but be careful it isn’t used too much as it can produce a kind of metallic sound in the background. It is much better to treat your room if possible.

  4. Is it possible to remove background noise like from a tv in the back round with different levels of noise
    I have a recording with very low voice recorded I need to listen it is a bit muffled and with the tv noise in the back round it’s near impossible to listen to the voice recording

    1. John – that’s a tough one. Here’s the problem. Noise removal works best in two situations – when the nature (mainly frequency) of the noise is very different from the thing you are recording (the “signal” – your voice, in this case), and when the noise is relatively low compared to the voice/signal. If neither of those situations is true – the background noise is similar to the recorded voice AND it is quite loud, you are not going to get a good result. Your best bet is to try to isolate JUST the TV noise in the background when there is no voice playback, capture that noise sample in a noise removal/reduction program, and try to filter it out. If the result makes the voice sound swirly or “under water,” try reducing the “amount” of noise reduction that is applied (usually a “percentage” option) and see if that helps. My gut feeling, based on what you describe, is that it will be difficult or impossible to get a good result. But it doesn’t hurt to try.

  5. exactly what I was looking for. Very effective for voice recording with cheap microphones. For me, the noise is reduced so much that it sounds unnatural. So I reduced the effect level to about 70% (70% wet). Thank you for the very useful tip

    1. You’re welcome, Mark. The artifacts you get from noise reduction are usually related to how much noise was there in the first place. The more noise, the more swirlies and other odd sounds you’ll hear after noise reduction. that’s why it pays to try and prevent as much of it as you can.

  6. Worked great to pull tape hiss out of a rip of a 40 year old cassette. Some audible artifacts in very quiet spots, but way less annoying than the hiss. Expected to have to work way harder to do it. Thanks for posting.

  7. This is a great tool! Thanks for the instructions. I have just used the tool to remove noise from two songs on an old tape recording (perfectly), but a 3rd, from the same session on the same tape is playing back with a subtle noise stutter throught the song, as though noise has been removed in chunks about a half second apart & bits of noise have been left behind. Any idea why that might be? I tried using noise samples from both before & after the song for the subtraction process. Or are there other ways to attempt to de-noise?

    1. Hi Justin. That is weird. Not sure why it would work fine for 2 songs and not for the 3rd. If you’re sure you removed the check mark from the “automatically build noise profile” box, I would suggest trying to either use the built-in noise reduction tool in Audacity (which is free). Or you might like a tool that I have started using that doesn’t even require you to sample noise. It’s part of the ERA Bundle by Accusonus. You can get the individual tools for ~$59 if you don’t want the whole bundle. I did a review of the tools, including the Noise Remover tool, here – Review Of Accusonus ERA Bundle (Amazing Vocal Plugins). the NR tool will obviously work on more than just vocals. Might be worth a try.

      Otherwise this might be a question for the good folks at the Reaper Forum –

      Hope some of this helps!

  8. Thanks for your response Ken. Yes, I have used the same procedure (of course unchecking the ‘automatically build noise profile’ box after the profile has been created) with all three songs, the problem one I have tried 4 times. I will try using the tool in Audacity, & if the issue remains then I’ll check the forum.

    Many thanks for your time.

  9. Thanks for point this out! Reaper is such a good program. I used this Reafir for reducing guitar buzz from P-90 pickups. The tracks are so much cleaner, and the guitar still comes through very well. On a bare isolated track, you can hear very faint loss of some of the Eq’s tweaked meant to reduce the hiss, but so worth it! Going to go back and fix a few more tracks!

  10. Ken, thank you so much for the tutorial.
    I’m trying to remove, or at least soften, animal sounds from the background of recorded speech. Some are softer than the human voice, others louder.
    Would the best approach be the one you described for John on February 19, 2018, to remove TV background noise?
    Thank you for your help!

    1. Hi Miki. This might work better in Audacity or Adobe Audition. I would try to isolate each sound and run the noise reduction on JUST the phrases that have THAT sound. Then repeat for a different animal noise (assuming they are different sounds). It would be like removing the mourning dove in this post: but doing it multiple times on JUST the places that have those mixed into the recorded speech.

  11. I am trying to remove the white noise from my guitar track and it won’t work. Any idea how I can remove the white noise without making the guitar go all ‘swirly’?

    1. Hi Avy. Assuming that you ONLY had the white noise selected when you fed ReaFir the sound that is ONLY noise, then this probably means you have too much noise compared to guitar sound. That swirly sound is the result of trying to remove too much noise. And it ALSO happens if you had some of the guitar noise in your selected sample. If there is too much noise-to-guitar sound, then the only thing to do would be to try a different noise reduction program. Maybe try the one in Audacity, which is free. Or some other recording program.

  12. Thank you so much for this guide! I am just getting into music production and was having a lot of trouble finding tutorials for Reaper to do simple things like reduce noise and improve sound quality on recorded tracks. This was a huge help and I will definitely be checking out the rest of your site!

  13. Hi Ken thank you so much, it only kind of works, in principle yes, I did follow instructions but I end up with metallic voice, how do I tweak this process to avoid the voice sounding like this?

    1. Hi Eva. One of 3 things is happening. 1. The checkmark was left in the “automatically build noise profile” box when you play back the audio. 2. Your initial selection of the audio you used to “train” ReaFir what ONLY noise is may have had a bit of the voice or a breath in it. Or 3. There was just too much noise in comparison to the voice in the first place. Or maybe some combination of the 3. Noise reduction can only do so much when there is lots of noise. And it will sound weird afterward. Hope that helps.

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