How to Remove Isolated Background Noises from Dialogue Recordings

Description:

Random sounds behind a dialogue track—such as beeps, squeaks, sirens, or coughs—can distract from the storytelling. Instant Process mode in iZotope’s RX audio repair software is the easiest way to Attenuate or Replace noises by selecting them on the Spectrogram and immediately applying the settings from theSpectral Repair module.

 

Sample:

Here is an example of dialogue track with the sound of a truck backing up in the background. We can hear and see the beeps as narrow horizontal lines around 1 kHz, and some high-frequency brake squeaks above 5k. The dialogue itself is represented by the curved lines between 100 Hz and 1 kHz.

Before RX:

After RX:

 

file
file

Steps:

  1. Open the audio file in the RX Audio Editor or send it via RX Connect.
  2. Engage Instant Process mode by clicking in the toolbar or pressing the [I] key.
  3. Select Replace from the drop-down menu next to the Instant Process button.
  4. Choose the Time & Frequency Selection tool  from the toolbar or by pressing [R].
  5. Select a single instance of the noise (you'll replace each beep individually).
  6. RX will replace that sound based on sounds around it, using the settings from the Replace tab of the Spectral Repair module.

Tips: 

  • Zoom for Accuracy. Zoom in on the spectrogram to make more accurate Instant Process repairs.
  • Adjust the Frequency Scale. If you aren’t able to clearly view and select the problem noises with the default settings, experiment by changing the Frequency Scale by right-clicking on the frequency ruler. Extended Log works particularly well for viewing and selecting problems in low frequencies, while linear works better for addressing problems at high frequencies.
  • Repair Each Noise One by One. Some unwanted events consist of several separate regions on a spectrogram,such as this example of the beeps from a truck backing up. In these cases, it's possible to achieve more accurate results by repairing several smaller selections one by one, instead of one large selection. Fast repair of many similar events can be facilitated by the Find Similar Events feature.
  • Fine-Tune Your Selection Using Spectral Repair. To fine-tune your selection area before immediately processing it, turn Instant Process mode off and open the Spectral Repair module. Make your precise selection and then click Process. You’ll need to repeat this for each individual noise. This solution can also be used in both the standard and advanced versions of RX 3 and 4.
  • Adjust Spectral Repair Settings. The Instant Process tool applies settings from the module selected in the drop-down menu. For example: in Attenuate mode, it’s applying the settings you currently have in the Spectral Repair Attenuate tab. If you find that you aren’t getting exactly the results you’re looking for, open the Spectral Repair tool and try different presets or settings.
  • Removing Noises in Each Channel Separately. As seen in the example above, when you make a selection in one channel of a stereo file, the selection will automatically be duplicated in the opposite channel. To make selections on one channel or the other, select the desired channel by clicking on the very thin grey lines labeled ‘L’ and ‘R’ on the left side of the Spectrogram. See this part of the user manual for more information.
  • For more information: Check out this article on the iZotope Blog.

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