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Sound Design Inside of iZotope RX

January 20, 2005

Repair and restore your audio:

RX 8

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While the RX Audio Editor is often used as an audio repair tool, it can also be used as a powerful tool for expanding your sound design palette. Create exotic sound effects quickly using the unique visual editing capabilities and processing modules in RX.


Here is an example of a hard effect of a pickup truck driving by and then that same audio file manipulated in RX to create a spaceship flyover effect for a sci-fi TV show.

Before RX:

After RX: 

Steps in RX Audio Editor:

  1. Open an audio file in the RX Audio Editor or send it via RX Connect. For this example, we started with a hard effect of a pickup truck driving by, recorded in stereo with two spaced shotgun mics.
  2. Experiment by making selections on the spectrogram using the different Selection Tools. You can preview your spectral selection by clicking on Play Frequency Selection button in the transport control.
  3. To replicate this spaceship flyover effect, begin by using the Frequency Selection Tool [F] to select all the frequencies below 300 Hz.
  4. Then select the Paintbrush Tool [B]
  5. Hold [shift] to add to the selection (use the [option] key to erase area from the selection) and draw a gently sloping curve that extends up to about 5k around the 5 second mark. This can help provide some dramatic doppler effect to complement the changes in amplitude and panning as the ‘spaceship’ flies overhead.
  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. Now you have created the filtered audio file. You can continue to manipulate this further with the Time & Pitch (ADV), Deconstruct (ADV), Channel Ops, or Plug-In modules, or just Export the resulting audio file for use as a new, unique sound effect.


  • Try the Magic Wand Tool. Click on different areas inside the spectrogram with the Magic Wand Tool [W] to reveal inspiring new sound effects inside any audio file.
  • Experiment with Pitch Contours. Inside the Time & Pitch Module (ADV), you can create a pitch contour that affects the speed of the audio file across a timeline for pronounced doppler effects and radical shifts. Try anything from a gentle linear slope to a fast sawtooth wave.
  • Push tools to their extremes.Try processing an audio file through the De-Click module with ‘Clicks only’ selected and the sensitivity set to 10. Use the Deconstruct (ADV) tool to remove all the tonal components from a grandfather clock to isolate just the mechanical noises. Use Ambience Match (ADV) to try and regenerate areas of the spectrum you filtered out. Use De-reverb (ADV) with a negative reduction amount to enhance the reverb of a piece of audio.
  • Reverse isolated parts of the spectrum. After making any selection, press [shift + R] to reverse that selection.
  • Try Iris 2. iZotope’s Iris 2 is a sample-based synthesizer that takes the power of the spectrogram and makes it available in a comprehensive synthesizer, optimal for complex sound design tasks. Layer up to four different samples, create radical spectral filter selections on each one, apply envelopes, map them across a MIDI keyboard, and apply LFOs, filters, and effects to create exotic new textures, ambiences, and sound effects. It also comes with over 11 GB of samples, ranging from classic foley effects to vintage synthesizers.

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