It’s always best to mitigate noise in your audio recordings before it can be picked up by a microphone. Unfortunately, this doesn’t always happen and it’s necessary to soften up that signal noise in post production. Most modern DAW’s (digital audio workstations, AKA audio production programs) use plugins to help with this process. And some DAW’s make finding those plugins a bit of a challenge. That’s why I’ve decided to post a quick tutorial on how to do noise reduction with the ReaFir plugin for Reaper.
Most unwanted noise in audio recordings tends to be constant throughout the length of the piece. Usually, these artifacts come from something in the environment such as a cooling fan or an electrical issue between the microphone and the sound input. When you have this type of continuous noise in a recording, noise-reduction plugins can come in handy as you’ll usually only need to set them once, and then they’ll apply the noise reduction to the entire track or noisy section.
To get started with noise reduction in Reaper, click the FX button on a track that’s got some unwanted noise. This will bring up the Add FX box, which shows all of the plugins and effects available to your Reaper installation. In the Filter list box at the bottom, type in “Reafir.”
Next, double-click the listing for the VST: ReaFir Dynamics Processor plugin. This will add the ReaFir plugin to your track and automatically open the plugin’s settings box.
From here, you’ll want to change the Mode drop down menu to Subtract and tick the checkbox next to that menu labeled “Automatically build noise profile (enable during noise).” These settings tell ReaFir that you want to remove certain frequencies from your recording and that you’d like the plugin to identify those frequencies automatically.
Now, align Reaper’s playhead so it’s at the beginning of a section of noisy audio but make sure that section doesn’t contain any speech or other wanted sounds. Otherwise, the plugin will think that the sounds you actually want to preserve are part of the problem and it’ll do it’s best to remove those, too! I also like to solo the troublesome track at this point, just so it’s easier to monitor when setting up the plugin.
Once the playhead is in place, click the play button (or press the space bar) and let the playhead go over at least twenty to thirty seconds of the recorded signal noise. Be sure to stop playback before you reach any of the desired sounds that are the intended focus of the recording. (If you were unable to stop playback in time, click the Reset button and start the process again.) Now, ReaFir has built a noise profile and automatically created a filter based on that profile.
Untick the checkbox next to the Mode menu but leave all of the other settings alone. Now, when you listen back to that track, you should no longer hear the unwanted noise.
Posted by Shawn Thorpe