How to make a robot voice changer filter in Audacity
One quick note before getting into this tutorial - the following advice is focused on Audacity! If you use other audio editing software, we recommend using Voice Changer for a far easier and effective solution. It even has a fully fleshed out robot pack, full of presets and profiles for your every robotic need! Anyways, over to the main article:
Think of the most famous robots you know from movie and TV history. As well as looking the part in their sleek, metal outfits, they probably had a sound all of their own too. Whether your robot voice is a series of bleeps and bloops like Star Wars’ R2D2, or a more sophisticated ‘synthetic’ voice like… well, Star Wars’ C3PO, the audio can matter just as much as the visuals and the acting when it comes to making a robot that makes viewers’ imaginations fly.
On the other hand, consider a movie like 2001: A Space Odyssey, whose starring robot, HAL9000, spoke in a mostly human voice. This fact that HAL doesn’t have a robotic voice shows that the level of technology in the fictional universe had reached a point where robot voices were just like human voices. Sometimes there’s not actually any need for a robot voice at all!
Even now, the robots of the movies don’t exist (although we wake up checking the news every day to see if the breakfast droid has been invented yet). So when the idea of the humanoid robot was taking shape in past decades, people had to work with what they had. Real human voice recordings were piped through strange effects to make them sound less human, and often more metallic. It’s interesting to hear the answer to the question “What does a computer sound like?” in early representations of robot voices from the silver screen.
Before reading the following about early sound engineering, check out something similar that was made a lot more recently. We use a robotic preset in this Voice Changer demo:
So how did early sound engineers make voices sound less human?
Pitch is a factor played with in the history of robot voices, using a harmonizer that was originally invented for musical applications, you could get a ‘double’ voice sound, thickening the audio to make it sound overlapped and phasey. A robotic voice doesn’t need to sound just like a humans, so having a very low or high pitch is acceptable, giving us a sense of a mechanical being rather than one made of flesh and bones.
Distortion is an effect you can link to the robot. Early ideas of artificial beings would have mirrored the speakers used in consumer products like radios and televisions. And to show a sound is coming from an electronic circuit, what better way than to make it a circuit that’s malfunctioning and distorting?
Phaser effects process a sound by sending it through electronic components that slightly delay different parts of the audio signal. A phaser is a great way to make a voice recording sound high-quality and understandable, but still retain elements of being synthetic.
Let’s dive into how you can create a robot voice changer free in Audacity.
Our original audio is raw, newly-recorded speech. This is free from too much background noise as we’ve used the tools in the ERA Bundle suite to easily clean up the background noise and reverb.
A key part of making our robot voice effect is to change the pitch of the audio. It’s possible to simply ‘Change Pitch’ using Audacity’s effects, but we highly recommend installing the MFreqShift plugin by MeldaProduction, which contains many more parameters to customize the effect. Once you have this plugin installed, it should be simpler to make a robot-style voice changer.
If you want to know how to change pitch in Audacity using the stock Change Pitch plugin, check out the Audacity manual.
Once MFreqShifter is installed, re-open Audacity and head to Effect >> Add / Remove Plug-ins. Find MFreqShifter in the list and hit Enable to have it appear in Audacity’s Effect menu from now on.
Now, load the plugin from the Effect menu. If you don’t see all the sliders to select (as shown in later steps in this walkthrough), go to the Options, uncheck Enable Graphical Interface and reload the plugin.
Now you should see the plug-in’s parameters laid out in a collection of sliders. We’re now ready to create the effect. Select Enable in the bottom of the window and let’s go!
The second control – Shift – is the one that’ll make the most changes to the sound of our robot voice modifier. After experimenting with the effect of this a little (also previewing the effect using the Playback buttons at the bottom of this window), we settle on a Shift amount of 124.9Hz. This exact amount depends on the voice you’re using and the effect you’re going for, so spend some time deciding here.
We can also bring the Dry/Wet control down below 100 to bring back some of the original voice sound, grounding the robot voice in reality a little more. We experiment with values for whacked-out we want it to be by the end.
We also change the effect’s Character, resting on the Ugly setting after a bit of experimentation and previewing.
The voice signal is actually running a little low. Because there’s space between the highest peak of our audio and the top of the panel, we can use the Normalize effect to bring the volume of our robot voice modifier up automatically within safe levels.
The audio now looks a lot healthier, but we’re still working on the sound.
Using a Compressor from the Effects menu, we can make the audio feel fuller and more powerful, bringing up the quieter parts and keeping the louder parts as close to what they were as possible.
Now, using the Graphic EQ effect, we can draw in a couple of curved boosts to emphasize certain frequency bands within our audio signal. This is another step that is dependent on your actual recording, but if you can emphasize some areas that give a nice robot-like character, or de-emphasize others that don’t, you can tailor the sound more heavily.
For an optional final step, we reach for the Phaser, reduce its Dry/Wet to 28, increase its Feedback and keep previewing to see if other parameters will help us. This effect may reduce the volume of your signal quite a lot, so either increase the Output Gain or apply Audacity’s Amplify effect afterwards.
Voila! Our robot voice modifier is complete.
With Voice Changer, you can process audio in seconds by simply selecting the effect you’d like to apply. This means you’re only a few taps away from a robot voice, a space marine, an old radio, or many other voice types. A lot, lot easier than this article's tutorial!