Be it poor gain staging, a noisy mic pre, a long unbalanced cable run or a vintage effects unit, line noise can creep into our tracks and muddy up a mix. The Dialogue De-noise tool in iZotope RX can help bring clarity and intelligibility back to your tracks.
Here is an example of a quiet nylon string guitar part that was recorded into a microphone with a very low output. Turning up the preamp added a significant amount of noise that makes it hard to bring the part forward in a mix.
Select the audio file in your audio or video editing workstation.
Open Dialogue De-noise as an offline plug-in, or insert it into the audio track.
Inside the Dialogue De-noise plug-in, choose Manual mode. This allows you to learn a noise profile and adjust the six multiband threshold nodes separately so that you can tailor the frequency response of the noise reduction.
Choose at least one second of the noise in isolation and press the Learn button to extract the noise profile. If you are using Dialogue De-noise as an insert plug-in, you'll need to play back the audio through the plug-in for it to learn the noise profile. When you stop playback, the threshold nodes will automatically set themselves based on the noise profile.
Click Preview or play to monitor the reduction. Begin by adjusting the Reduction slider to add or reduce noise reduction. Beware of the watery artifacts that can come from over-processing, and remember that multiple passes of De-noise with more conservative amounts often works better than one pass of aggressive noise reduction.
To tailor the frequency response of the noise reduction, adjust any of the six multiband threshold controls.
If processing offline, render the noise reduction by clicking the Process button.
Repeat the previous steps multiple times with small reduction amounts to reduce noise gradually.
Try Spectral De-noise. For stubborn noise problems, the Spectral De-noise plug-in included with RX can tackle complex noise profiles with more precision and control.
Use in moderation. Noise reduction artifacts can be more distracting than the noise itself! Be gentle and use multiple passes of offline processing if necessary. This will often lead to a better sonic result than one instance of the Dialogue De-noise plug-in with very high reduction amounts.
Add a high-pass filter. A high-pass filter ahead of the Dialogue De-noise plug-in can remove rumble so that the Dialogue De-noise algorithm can focus its multiband detection on subtle changes in the noise profile.
Treat the high-mids gently. When in manual mode, set lower thresholds on the high-mid frequencies as this tends to be where vocal artifacts are more audible.
Know your noise. Is your noise constant or varied throughout? Is your noise broadband or tonal? RX has customized tools for different types of noise. You can learn more about identifying these different types of noise in the article Identifying Audio Problems.
Automate each threshold node. All of the parameters of the Dialogue De-noise plug-in can be automated when it is in Manual mode, including the individual threshold nodes, so that you can adjust settings in real-time along with your program.
Sculpt with EUCON. The Dialogue De-noise Plug-in is EUCON compatible so you can configure any of the parameters to be available right on your control surface for real-time adjustment and automation.