I'm not great at editing audio. Any tips on how to use Audacity to edit a clip to sound more like a robot?Robots are tricky. As with anything else we do, the performance is key. What kind of robot is it? What kind of personality? Is it a good guy or a bad guy? Once that performance is nailed down, that's what will dictate the effects placed on the voice.
The most memorable computer voices are often just regular human voices, completely created out of the performance, like HAL9000 or the computer on Star Trek.
Usually you can get away with a little EQ, some compression, and a light metallic distortion effect to make it sound like a normal voice being played through a speaker. If the character dictates more "mass", then you can drop the pitch just a touch, and add a very light reverb.
If more brutal effects are needed, you can turn to Ring Modulation or Vocoding to add specific metallic or synth based elements to the voice, examples of this would be The Daleks or Cybermen from Doctor Who.
Doing a search for "free ring modulation" or "free vocoder" should give you some VST plugins to drop into Audacity.
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