THX 1138 sound effects

March 7, 2009 5:22 PM

Basic Sound Processing: Using software, how would I process recordings of the human voice to achieve the effect heard so wonderfully throughout George Lucas' THX 1138?

I'm thinking specifically of the shortwave-type chatter coming from the supervisors during the cleanroom scenes, which have some modulation going on, especially the parts where a high harmonic seems to drift into earshot. See here: the part from 0.28 onwards: Victor oh seven niner - you're making contact - at point zero zero three. And again at 0.40 onwards - that's it - slow down a little bit you're overriding.

It's not just the overall sound quality that's appealing, it's also the slow modulation, as if the signal being received is drifting in and out of focus.

Is there a standard filter that can be applied to the source waveform? A complex series of flanges and phasers and modulators? Or would I have to travel in time and space into a dystopian underground city and get a job in a control centre?

posted by Beautiful Screaming Lady to Technology (9 answers total)

Take a look at this link. I'm pretty sure that using a ring modulator, a ring modulation if you will, will provide the effect.

For Logic, the plugin is called Ringshifter but there are probably similar versions for other sound programs.
posted by fantasticninety at 5:35 PM on March 7, 2009

That sounds like a shortwave SSB transmission with the receiver's BFO drifting in and out of tune. I can do it with the proper radio, but I don't know how to do it with software.
posted by DarkForest at 7:25 PM on March 7, 2009

DarkForest has it--I was watching the THX commentary with the audio engineer a few weeks ago, and the effect was done with two shortwave radios going in and out of tune. That said, I have no idea how to do that with software (or, for that matter, how to do it with shortwave radios).
posted by Admiral Haddock at 8:31 PM on March 7, 2009

Variations on his kind of effect can be done with amplitude modulation (multiply the signals by one another), frequency modulation (use the signal to control the frequency of an oscillator), phase modulation / waveshaping (use input signal as an index to a wavetable with a secondary signal). These are all basic synthesis techniques you can do in pd / max / csound / reactor / audiomulch / whathaveyou. If they were tuning a short wave radio to get the effect, that would be closest to a frequency modulation (frequency modulation was my first guess when I heard the clip)
posted by idiopath at 8:56 PM on March 7, 2009

frequency modulator vsts
posted by idiopath at 8:57 PM on March 7, 2009

I remember watching the student film version that came with an anniversary edition and thinking that it was ring modulation with the frequency shifting modulating the dialog. It's an appealing effect.
posted by mnology at 11:55 PM on March 7, 2009

I think you could also do something like this with a vocoder, say, if you modulated the pitch with a low-frequency oscillator of some sort...? That would be my first inclination.

This is also an interesting page linked to from the above wikipedia page...seems like you have a variety of options, try 'em out and see what works best! Any of these would be pretty easy to do in SC3 or Max/MSP, PD, etc.
posted by dubitable at 2:50 PM on March 8, 2009

It's a combination of distortion and a ring mod effect. The "fade" is from altering the pitch of the ring mod.
posted by neckro23 at 8:20 AM on March 9, 2009

Ring modulator with modulation of the 'ring' frequency. (Nice demonstration here.)
posted by Sys Rq at 6:42 PM on October 17, 2009