Noise reduction Audio Tips
It’s a well known fact that noise reduction introduces unwanted artifacts into your audio recording. The processing of dynamic high frequency analysis introduces freckles, glitches and that underwater effect across the high frequency spectrum. Not good.
Is a Remedy Not a Cure
The good news is that using noise reduction subtly and complimenting this process with EQ can bring noisy DSLR recordings back to life.
Use the ‘Learn’ Function
First off, all noise is different depending on the type of mic used in the recording, as well as it’s placement, the amount of gain applied and a number of other factors. Noise Reducers can come with a ‘learn’ function. ‘Learn’ analyses the nature of the noise attached to your audio and creates a ‘noise profile’, which makes for more accurate noise reduction.
- Insert a Noise Reduction plugin on your audio channel or clip
- Look for the ‘Learn’ function of the plugin and click it. Press play running your noisy audio through the plugin for some time. Analysis of the noise spectrum will begin and reduction will perform more efficiently now that your ‘noise profile’ has been made.
Play with the Threshold Control
Noise reduction works best when you constantly play your audio source through the plugin and reduce the ‘threshold’ down very slowly.
- Listen not only for reduction of hiss and noise but also increases in unwanted artifacts. Find a balance between satisfactory reduction of noise and unwanted artifacts such as fractals, crackle and smear.
- Don’t worry too much about audio sounding dull and underwater, this can be corrected later. However, reducing hiss will reduce clarity, sparkle and intelligibility so the key is to us the effect subtly. Find a balance between a natural sound and a reduction in hiss and noise.
Brighten and Recover
Now that you have reduced hiss and noise to a satisfactory level you’ll notice the source audio feeling dull and subdued, but only slightly. The subtle use of DeNoisers is key here, to avoid unwanted artifacts from effacing the audio. Using EQ, Compression and Gain can recover from this underwater effect. EQ is the tool you need at this stage.
- Insert an EQ plugin directly after the Noise Reduction Plugin on your audio channel
- Look to engage the ‘High Shelf’ normally located on the far right of the EQ. This will lift frequencies in the high range bringing clarity, brilliance and air back into the audio recording.
- Select a frequency between 10,000Hz (10kHz) and 12,000Hz (12kHz)
- Set the gain from between +3db and +6db
- Set the output gain on your EQ plugin to +1.5dB
Zone In On the Sweet Spot
With all audio, no matter the source, there will be a sweet zone of frequencies in the high range that when subtly boosted will add sharpness and intelligibility. The human voice piques our interest at around the 1,000Hz (1kHz) range. Our ears have natural abilities at these frequencies, which is why we can often pick out distant human voices despite being smothered in external environmental sounds.
- Set a frequency band control to 1000Hz (1khz)
- Set it’s gain control to +6db
- Slowly sweep the control from 1kHz to 9kHz listening carefully to your camera audio recording.
- Find a spot where things pop out a little more but don’t re-introduce the noise you were experiencing.
- Now reduce the gain of that EQ control from +6dB down to +3dB to settle on a subtle boost of the sweet spot
Perfection is Inhuman
It’s worth considering that recording perfectly crisp, clean, super-quiet audio is not possible for the majority of us, and nor is perfect audio always desirable. Some noise can add analogue character to a recording and noise reduction plugins can only go so far as to tame problem source audio. That said, noise issues are a common problem and the key is to use DeNoisers subtly, then compliment this transparent processing with EQ.
I hope this article is inspiring and helps you tame unwanted hiss and noise in your DSLR recordings.. let us know how you get on!
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