Sound designer Tim Prebble keeps a prolific, enthusiastic and informative blog at his substation.co.nz website, often sharing experiences from the set of film productions. It’s the sort of place where he’ll link to a Fatboy Slim video one day, and then theorize on the value of temp tracks the next.
Late last month, he went into detail on what he calls the “backwards reverb” effect, in which an echo of a sound is heard before the sound itself comes into focus. “I think why the technique is very useful when applied in an appropriate context,” he writes, “is because it essentially generates interesting tonal sounds that are directly related to the sound they precede.” He also provides step-by-step visualization of how the effect is produced:
It’s a sound often utilized in horror films, to signify a supernatural state, and in scenes in which individuals regain consciousness as they come out of a black out. It’s also something I associate with some of the eerier Led Zeppelin tracks, in which Robert Plant’s voice seems to arrive ahead of schedule.
Prebble uploaded two audio examples to his blog, one brief vocal (MP3) and one from the sound design for the film Perfect Strangers, on which he worked (MP3). Perfect Strangers opens with the image of an onion being cut by a knife. He describes how he accomplished the final audio as follows:
I realised that when its seen in a theatre that onion would be HUGE so I started experimenting with accentuating the sound of the knife cutting into the onion and the pieces of onion almost dancing as they came off the knife. I recorded a lot of very close up onion cutting sounds, at various speeds & got the sequence working kind of as I imagined… After I played it to the director, she liked it so much she decided to extend it prior to the film starting, starting off very slow & almost abstract & then becoming more real until it reveals onscreen… So I pitched down some of my onion cutting sounds and recorded more, slower ones but I needed a means of pushing them away from reality a bit – ahar! Time to try a backwards reverb on it. So I reversed a number of the sounds – the cutting sound and especially the wooden clunk as the knife hit the cutting board – applied various length reverbs, then reversed those reverbs & resynced them with the other ‘real’ effects… magic! It took some manipulating to make the elements all feel a part of the same moment, but it worked a treat and i remember playing the sequence to the composers on the film and they couldnt work out how I had done it…. when we mixed it we also had some fun by placing the start of the onion cut in the surrounds, so the slice basically passed through the audience, until it impacted at the front…. have a listen, its not quite as coherent without the images but you can get a feel for merging backwards reverbs with real effects…. You’ll notice we start introducing elements of the ambience during the transition from surreal to real, by the third chop you can hear the fridge and then you start to hear the kitchen etc…. bear in mind this is a stereo crash down of the 5.1 FX stem… crunched to mp3….Read the full post at substation.co.nz. More on Prebble’s film work at his imdb.com listing.