Recording FX at 96k

Last weekend I did my first FX recording session for Laundry Warrior I’ll talk about the 96k aspect in a moment but so far I am just providing temp sound effects for the picture editor. Personally I believe it is much better to provide temp FX that are original. The main reason for this is that the last thing you want is a director falling in love with some generic library sound effect which, even though it may not be the best sound for a moment, through the repetition of cutting & screenings a scene or moment might later feel weird without it.
Providing temp FX also gives me a chance to see some scenes from the film & to start thinking about what we are going to need to find. When I worked on 30 Days of Night, I started work the earliest I ever have on any project, ever. Literally at the end of the shoot, once the picture assembly & then a first editing pass of each scene had been completed, they turned over a quicktime of the whole movie, scene by scene, for me to provide temp FX. What this equated to was a very fast pass through the movie, cutting crucial sound effects & ambiences, focusing particularly on sounds that directly contribute to the story. I would then send picture editorial a little stereo mix of my temp FX for the scene, which they would incorporate & also cut as they tightened up the scenes.
But what was interesting to me in hindsight was that my process became informed primarily by instinct & pragmatism. Instinct because it was my first look at a scene and I would just dive in amongst it… and pragmatism because i knew I couldnt make it “perfect” and some sounds I just either didnt have immediately at hand or couldnt provide worthy versions of… but the funny thing about first impressions was that some of them made it into the final mix! Of course every scene benefited from further work, from all of the team of sound editors over the six months of sound post production, but in terms of overall approach some initial ideas turned out to be very valuable. The other benefit of this approach is that it starts the ongoing conversation with the director about the sound of the film.

So here is the little collection of swords I rustled up for a first recording session. Most are borrowed from the foley room at Park Road Post (who knows how many films these swords have already been heard in!)

The more observant amongst you will notice a few non-swords… on the extreme right is a small metal crowbar, which is very resonant. Beside it is a Tibetan singing bowl and below it a pair of finger cymbals. If you have never played with a singing bowl before then you really should experience it – I bought mine at Trade Aid By gently rubbing the wooden beater around the ouside of the bowl a very pure tone is created, in fact so pure that apparently the bowls are given to trainee monks who are learning to meditate, as it takes a placid form of concentration & effort to create a continuous tone… The finger cymbals are interesting as they are much higher frequency than the singing bowl, and being attached to a piece of leather means they can be moved while they are ringing, creating small natural dopplers and beating tones….

Ok so why record at 96k? I have read many a rant in online forums by people almost offended by the concept, you know how they go; “why bother, you can’t hear that high? who are you recording it for – dogs? blah blah…” Well I can provide an answer that proves those naysayers wrong, without a doubt, because unlike them I have actually tried it & found what the benefits are, for me.

In a nutshell, there are two aspects I find beneficial about recording at high sample rates. Firstly, I am capturing a lot more data than usual. I do all my editing etc at 24 bit 48k, as that is what the Euphonix mixing desk is natively working at at Park Road Post. But when I am working on creating sounds I am often interested in manipulating them in many ways & having more data to start off with means the artefacts created through manipulation are far less readily apparent. Take a simple pitch shift. I love to hear sounds at half speed and at quarter speed, as it both slows the evolution & envelope of a sound but also adds gravity to it, through lower frequencies becoming more dominant. But at quarter speed you are talking about a two octave pitch shift. Most software I have used starts to sound bad after a one octave shift, simply because at half speed every second sample has to be artificially created, and at quarter speed the artefacts are doubly as bad. BUT with the much denser data stream of 96k I can play at half speed and it sounds as good as my old 24 bit 48k stream did! This is a serious advantage!!! The same benefit applies when you timestretch a sound… working at 96k I suddenly discovered plugins working sucessfully way past the point I would normally avoid….

The other aspect of 96k recording is that even if we cant hear above 20k, that doesnt mean there isnt sound up there. I remember reading a beautiful quote from someone watching a Tui (a bird native to New Zealand) sing, and they noticed that half the time the Tui was singing they couldn’t hear what it was singing as it was off the top of the persons hearing range. So presuming I have a microphone that has a higher frequency response than my ears I could record that Tui at 96k, pitch it down an octave and listen… see what I mean? The same theory applies to any sound generating object that creates high frequency harmonics, especially metal which is very resonant…
So recording sound effects it makes a lot of sense to record at 96k. Sure it creates twice the amount of data but I now tend to import my recordings into a 96k ProTools session and create pitched versions of the sounds before I output to a 48k session for syncing, cutting etc…

Microphones that capture frequencies higher than 20kHz include Sennheiser MKH 800 which is flat to 50kHz, the DPA 4004 and 4007 (flat to 40kHz) and Earthworks microphones such as the QTC50 which is flat to 50kHz (their preamps are flat to 100kHz!) There are also some good technical papers on the Earthworks site, including this PDF: the world beyond 20kHz

Ok, I will post some 96k recordings as soon as I get time to output them, but it might have to wait until after Nyepi….

3 thoughts on “Recording FX at 96k

  1. Pingback: When Should I Record At 96kHz?

  2. Pingback: Designing Sound » More than 50 Articles/Tutorials about Sound Design, Recording and more, Plus Wooshes Sound Design

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