Intelligent Noise ReductionOne of the most critical things I need when post processing audio is a noise reduction filter. The room is pretty quiet yet there is still audible room noise. The noise sits around –60dB which is pretty far down but noticeably audible for anyone listening on headphones. I also like to use a noise gate to remove low level breathing, lip smacking and other distracting sounds. The problem is if you use a noise gate with room noise and you don’t add a track of room noise, it’s very noticeable when the gate kicks in. A properly used noise reduction filter makes this problem go away. A badly used noise reduction filter adds those tinkling high frequency artifacts that to my ear, are worse than the original noise. In theory they’re quieter than the noise but they are much more noticeable. Reaper has a built-in plug-in called Reafir that is a multi-purpose tool for audio processing. So far I’ve only used it for noise reduction. Here’s how.
- The first step is to use the Mode dropdown and select the Subtract option. Then select a piece of audio that has only steady room noise. No clicks, no chair sounds just whatever ambient noise you want to remove. You can loop this section of audio.
- Then enable the checkbox for Automatically build noise profile (enable during noise).
- Select an FFT size. I tried all of them and I ended up just using the 4K FFT to build the profile. Now hit Play on the transport bar and it will build up a waveform in the bottom of the display. Hit Stop. If the red line doesn’t move to follow the noise then something isn’t working. Make sure the checkbox in the upper right corner is enabled.
After I had a noise filter I liked, I added a noise gate to my FX chain. I wasn’t able to detect when the gate kicked in and out but all the low level breath sounds and noises were gone. When I turned the gate off I could hear some mild artifacts on my breathing but since the gate eliminated this I didn’t really care.
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