Using your own voice and one effect in Audacity, you can turn yourself into a computer.

What You Will Need

• Audacity. It's free and easy to use.
• Plugins - You won't need any extra plugins for this effect.
• eSpeak (optional) - If you don't have a microphone or don't feel comfortable with your voice, you can use this for text-to-speech synthesis. The output isn't amazing, but it can suffice and is unencumbered by any licensing restrictions.

Creating the effect

1. Take a recording of your voice in Audacity. You can load any WAV output from eSpeak in as well.
2. Select all of the sound by using the selection tool or press Ctrl-A.
3. Go to Effect->Delay... from the menu.
4. In the dialog that appears, type in the following values:
   • Decay: 6
   • Delay 0.009
   • Echoes: 30
5. This will apply the effect once on the voice, and it may not sound like it did much of anything. Press Ctrl-R to repeat the effect 2-3 times. Play it back each time you apply the effect again. I've found 3 to be enough in most instances.
6. You may notice that your waveform has grown in amplitude and may have some artifacts on the higher frequencies. To bring it back down, click Effect->Normalize..., and use the default settings. In 99% of cases this will do the trick.

Optional

If you're looking for a more sinister-sounding computer, you can pitch shift the voice (Effect->Change Pitch...) prior to adding Delay in Step 3. 1.5-2 octaves is usually enough to do the job.