Tutorial: Audio Censorship with Reaper and OSARA

In a Mastodon post, Quin asks:

I’m using the Voxengo beeper plugin. I created a new track, and added Beeper as an effect. But now, how do I tell it where to apply? I have a very narrow portion of audio I want to sensor.

(Source: https://dragonscave.space/@TheQuinbox/111343026816962282)

The mentioned plug-in, Voxengo Beeper, is intended for content protection rather than censorship. For instance, you might tell it to insert some noise every X seconds into an audio file being shared as a demo, so that it can’t be used for its intended purpose without a license.

From a quick search, there’s an alternative called CensorCut, which has a beep parameter that can be automated or triggered with MIDI. This could work if you’re censoring a lot of audio, but it’s also doable with stock Reaper JS plug-ins. With thanks to Jamie Teh and Patrick Perdue for commentary and tips, let’s dive in.


A project with at least one track, and some audio on that track that you want to apply censorship to. I also assume that you have Reaper set up as you want it, with OSARA installed and so on. All commands are for Windows with an unmodified OSARA keymap.


  1. Navigate to the appropriate track, and open its effects chain by pressing F.
  2. Search for, or otherwise locate, the “JS: Tone Generator” effect, and add it to the track. Be warned that it will start playing a continuous tone straight away, even while the project isn’t being played.
  3. If the continuous tone is getting in the way of you using your screen reader, temporarily mute the track with F5.
  4. Press P for the OSARA effect parameters dialog. Set “Bypass (7)” to “bypassed”, then press Enter.
  5. If you previously muted the track, press F5 to unmute it, and you should find that a tone is no longer playing.
  6. Press Shift+L to view the envelopes for the current/last-touched track.
  7. Tab to the input labelled “Highlight:”, type “bypass”, tab once, and press Down Arrow. You should find a checkbox labelled “Bypass Tone Generator”. Check it, and press Enter.
  8. Press Alt+L until you hear: “Bypass / Tone Generator envelope armed”.
  9. Move to the point on the track where you want your censorship to begin. Press Alt+Shift+E, type “normal” and press Enter.
  10. Move to the point on the track where you want your censorship to end. Press Alt+Shift+E, type “bypassed” and press Enter.
  11. Press P again for the OSARA effect parameters dialog. Set “Dry Mix (dB) (1)” to -120.0 so that the original audio is completely cut, and optionally adjust the frequency of the tone. For example, 1KHz (1000Hz) is commonly used in TV, radio, etc.
  12. Repeat for any other desired instances.


  1. If you have multiple effects on a track, P will open a context menu to choose between them. Select the tone generator whenever the steps prompt you to open the parameters dialog.
  2. These steps set the dry mix level and frequency for the entire track, so that they’ll be the same each time you censor. If you want them to differ for a particular instance, you can use the Shift+L window to show these or any other parameters as envelopes too, and set envelope point values accordingly.
  3. When using bypass as the parameter for an envelope point, square is selected as the point shape automatically. If you automate other params, like frequency or dry mix, you should set the shape to square yourself, or experiment with other shapes to gauge their impact. For instance, you may want the source audio to fade out and in, instead of being sharply cut and restored.