Once upon a time it took racks full of bizarre transistor-ridden contraptions to make the astounding voice effects heard in Dr Who. Fortunately nowadays technology has advanced sufficiently that the same voices can be recreated at home on your PC using a sound editor such as Cool Edit 96

I used to say as a joke that the BBC only ever had one effect which they used to do all their "alien" voices. This isn't of course strictly true. They've had two effects since the Seventies when the Cybermen changed their voices. The two effects in question are pitch shifting and ring-modulation.

Ring-modulation, the effect responsible for the Daleks, Morbius, K9, Zygons and Davros amongst others, is in essence really just the multiplying of one low frequency wave with the voice waveform. Depending on the modulating wave - it's frequency, levels of harmonics and shape, the effect would vary from metallic grating to a strange bubbly sound. You will be pleased to learn that Cool Edit 96 has a ring modulation feature too for you to recreate these classic sounds.

Once you have recorded your voice, highlight it and then go to Generate then Tones. Check the Modulate button in the bottom right and you're away! The waveform you create will be applied to your voice. To get a basic "Dalek" sound choose a triangle wave of around 40 hz with few high-level harmonics. One click of OK will render your sound. Experiment using different sorts of modulation wave to get different effects.

The modern Cyberman voice is achived with the BBC's second voice effect - pitch shifting. This allows a voice to be deepend in pitch. A similar effect can be found in Cool Edit under the Transform->Time and Pitch menu. The cyberman voice is in essence two differently pitched voices over the top of each other. The end result can also be enhanced a little by adding a warbling flanger effect on top. I suppose that should count as the Beeb's third effect really...

One thing to remember when doing such voices is that the sound is as much in the performance as in the effect. If you don't do a pretty good impression of a Dalek to begin with, no amount of Dalek "effect" will improve it.

These demonstration voices you can download as automatic scripts for Cool Edit here. There is a Dalek and a Cyberman included. Save the file in your Cool Edit directory and use it through Options -> Script and batch editing. This script works with Cool Edit 96 and Cool Edit 2000. Their use can be heard in the FloorTen Audio stories "Regeneration of the Daleks" and "Jubilee".

Happy exterminating!