Creating Futz Audio Effects with RX


‘Futz’ audio generally refers to highly processed dialogue tracks that make the audio sound like it’s coming from a telephone, a small speaker, an alien spaceship, or whatever the story demands. By making frequency selections on the spectrogram inside of the iZotope’s RX audio repair software, we can apply radical filtering effects to create the sense that the actor’s voice is coming through a telephone or anything else you can imagine!



Here is an example of a dialogue track where the actor’s voice needs to sound like it’s coming through a telephone. With RX Audio Editor, we can easily filter out specific parts of the frequency spectrum to create this telephone sound.



Steps in RX Audio Editor:

  1. Open the Audio File that you want to apply the telephone effect to, or send it from your DAW/NLE directly to RX using RX Connect.
  2. Choose the Frequency Selection Tool [F]  to make horizontal selections in the frequency domain across the entire timeline.
  3. Make one selection between approximately 300 Hz and 4 kHz to isolate the spectrum represented by a telephone or other device.
  4. You can preview your spectral selection by clicking on Play Frequency Selection button  in the transport control. Adjust selections to taste.
  5. Hold [shift] to add any additional frequency areas to the selection.
  6. To commit these frequency selections, first Invert the selected area [Control/⌘ + I] and then press [Control/⌘ + S] to Silence the frequencies you wish to remove.
  7. Play back the result. You can undo these steps to make any additional adjustments.
  8. Export the audio file as a new audio file or click Send Back if using RX Connect.



  • Different Sounds for Different Devices. Some re-recording mixers like to create distinctive telephone effects for the different models of phones being used by the characters as props. This could be done by using different frequency areas or distortion effects to distinguish between the different types of phones.
  • Not just for phone effects. Experiment with different spectral selection shapes to create other unique futz effects. Also try processing spectral selections with radical treatments using other modules from RX Advanced such as Deconstruct or Time & Pitch (ADV).
  • Add Distortion. A subtle amount of distortion can help make the telephone effect sound more authentic..
  • Add Ambience. Any dialogue segments that are not being heard through the phone may need a reverb effect to help give them depth and contrast in the context of the scene.

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