Noise Reduction

Removing unwanted noise from a recording can be challenging. Not all of us have the luxury of a perfect recording environment with optimal gear.

Try Multiband Compression/Expansion

Using Waves C4 for Noise Reduction

What stood out in this recording was the high-frequency noise. Pay close attention to the high frequency range.

It's recommended to use headphones to fully capture the nuances in the video.

Method

Here's what the Waves manual suggests:

1. Find a section of audio where only noise is present and loop the playback.
2. Listen to each band separately using Solo function and determine the desired noise reduction for that band. Adjust the Gain to match the desired noise reduction (a negative value).
3. Set the Range to compensate for the gain reduction in low levels; it should be the inverse of the Gain. For instance, if Gain is set to -12dB, the Range should be +12dB.
4. As you preview the noise, adjust the Threshold in each band, ensuring it's just above the noise energy. This way, you achieve the desired noise reduction for that band.
5. Utilize a hard Knee setting (maximize the Knee control in the Master control section).

Now, preview a section where the desired audio signal is present. Ensure it's well above the threshold(s) so that no gain reduction occurs (indicated by the yellow line being at 0dB gain).

Focus on problematic areas, especially where the audio fades or during softer sections where the sound gets closer to the noise level. Here, the Threshold requires careful adjustment to prevent significant degradation of the signal itself.

Other Tools and Approaches

The C4 method described above can be replicated with any multiband compressor, provided it supports the expander mode.

Using Logic Pro Multipressor

This involves using the tool as a multiband expander instead of a compressor.

Again, headphones are recommended to discern the details in the video.

Steps:

1. Disable compression.
2. Enhance Peak sensitivity by reducing the Peak/RMS value. This ensures the expander reacts swiftly.
3. Modify the Attack and Threshold in the Expander section.
4. Loop the noisy segment you aim to filter.
5. Solo and adjust each frequency band individually.
6. Adjust the Ratio and Reduction (-50 dB) in the Expander section until the noise is eliminated.
7. Gradually decrease the Reduction to an appropriate level.
8. Iterate through each band in succession.
9. Playback the desired audio and fine-tune the settings.
10. Aim to get the Gain Change moving towards 0 to let sound through.

To me, it has been more difficult to get a satisfying results with the Multipressor compared with the Waves C4 method.

Reaper ReaFir Noise Reduction

Reaper offers an intriguing FFT Dynamic Processor plugin named ReaFir, which can be used for noise reduction.

The output tends to have a "swoosh" characteristic, a common feature I've noticed with many other noise reduction tools.

Years ago, I experimented with Waves X-noise, and while it delivered commendable results, it came at a hefty price due to its specialized bundle. Moreover, it introduced a lag in the system, making live recordings a challenge. A frequent issue with most noise reduction tools is the propensity to produce "swooshy" artifacts. Based on my experience, multiband compression/expansion offers the most satisfactory outcome and introduces minimal distortion to the sound.

Nowadays, I would strongly recommend using iZotope RX. In my opinion, it stands out as the best tool for audio clean-up and noise reduction.

For those venturing into audio editing, remember that technology and tools are ever-evolving. Always keep an ear out for new developments. Feel free to share your experiences and tools you find effective.

@ Hans E Andersson, HEAMEDIA 2009