ReaFIR is an FFT based dynamics processor, and one of the suite of plug-ins that come with Reaper. You can download ReaFIR for free, even if you don’t have Reaper. ReaFIR can be used as a linear phase filter or crossover, or a sculpting tool somewhat like TrackSpacer. But today, we’ll look at its noise reduction capabilities.
- Reaper has ReaFIR — a built in tool that does noise reduction. Here’ I’ll explain just how to reduce background noise, hum, or room noise.
- ReaFIR works very well on steady noises such as hum from a guitar amp, or a computer fan, or air conditioning. This technique is not designed for sudden, or random noises.
- You’ll need a few seconds of the noise, by itself, for this technique to work.
ReaFIR listens to the content you want to remove, and builds a noise profile of that sound. Then, it subtracts that sound from your track.
Step-By-Step Noise Reduction with ReaFIR
- On the track you wish to fix, locate a section of audio containing only the noise.
- Add ReaFIR to the track.
- In ReaFIR, Select ‘Subtract’ from the ‘Mode’ dropdown, click the ‘Automatically build noise profile (enable during noise)’ to select it.
- Select ‘Precise’ in the ‘Edit mode’ dropdown.
- The FFT size determines the block size used for processing, and therefore the precision at which ReaFIR operates. Larger block sizes also use more CPU.
- Navigate the the noisy section and play, taking care not to play anything but the noise.
- Uncheck the ‘Automatically build noise profile (enable during noise)’ box, and listen back.
- If you want more or less noise reduction, use Ctrl/Cmd and a left-click drag the noise profile up or down. If you hear artifacts (robotic or phase/flange sounding), pull it down until the sound clears up. In general, if it’s not a completely steady sound, you’ll want to reduce the level of noise reduction a bit, as the noise profile will include noise that isn’t always present, and ReaFIR will remove that from your content.
- The ‘Reduce artifacts (less effective)’ checkbox is another alternative, if you hear artifacts.
- If you still hear a bit of noise in silent parts of your content, you can use ReaGate to remove or reduce that.
- A high-pass filter (ReaEQ will work fine for this) before ReaFIR will help remove some of the low noise and rumble.