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Binaural sound recording

clive

clive

Hi guys for the last year I've been kicking round in my head a different way of recording sound for film. I had intended to do by Masters Degree on this very thing, but as it and my film production abilties are limited by money at the moment I thought I'd pass it on and open it for discussion rather than sitting on it.

This is the basic thinking. Currently, if you think of the audiences' eyes as the camera and the mirocphone as thier ears, there is always a spacial difference between the two that doesn't correspond to our everyday life experience. We solve this problem in post production by paning the sound to the right place realtive to the screen, but it's always an artificial solution and it destroys the spacial information that the sound carries to the brain.

I decided to look into microphone profiles and see if there was one that best matched human hearing and discovered a whole world of sound recording I'd never come across, binaural. Basically they are two small microphones that are placed into your ears and perfectly mimic human hearing, including the spacial information.

What I've been playing with is the idea that the camera operator could wear the binaural microphones and be the ears of the audience as well as the eyes. However to make this work would mean always using the same fixed focal lenght for the lens for all shots, because you'd need a constant relationship between the visual and the aural. This is effect cuts down a lot of shot options, it also means that the camera has to be acoustically baffled so that it's silent.

To back this up I think that all the actors would need to be wired with radio mics and each mic recorded onto it's own stereo pair, that way the clean "radio mic" sound could be laid over the binaural atmos and panned into place.

There's a resonable amount of information about binaural recording out there, it was used for music recording in the seventies, it's a particularly good at live concert recording. However, I've never found a film maker who has looked at it yet, so it's virgin territory.

The real problem with binaural is playback. On headphones you get perfect 3D sound, but speakers tend to cancel out some of the effect. Foor the Masters degree I was palnning to shoot short films, record the sound binaurally and then palyback the results in a local cinema to get gauge the results.

Anyhow. That's what I've got on this for the moment, but I'd be interested in anyone elses take on it.
 
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The camera operator would also be required to not move their head at all while shooting. The right ear would also be blocked by the body of the camera...You'd probably be better off recording the ambient in stereo separately. I read somewhere (can't quote source, don't remember) that there were early sound tests done with stereo sound in which the sound editors placed the voice tracks in the correct space locationally for the actors position on/off screen. Apparently it was so disconcerting to the audience that some of them got headaches from having to shift their focus so often. This is the reason that the voices are specifically put in the center of the space. Any off axis sounds tend to be nothing more than cues to shift your attention in that direction. Ambient noise was quite popular in the movies due to its' use in MASH (the movie). I can't watch that movie very often, it's soundscape is too cluttered. It gives me a headache, literally. I'd be interested to hear your findings, but I would try just recording the space in stereo with 2 standard cardioid mics about 30-90 degrees off axis, then lay that under as room noise and see how it works out in a scene or two.
 
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but I would try just recording the space in stereo with 2 standard cardioid mics about 30-90 degrees off axis, then lay that under as room noise and see how it works out in a scene or two.
Click to expand...

That's interesting. I'll try that. I also spoke to one sound guy who used two plate mics with an insulating tile between them in order to get the spatial split. I'll try both of them once I've got some spare cash again.

I read somewhere (can't quote source, don't remember) that there were early sound tests done with stereo sound in which the sound editors placed the voice tracks in the correct space locationally for the actors position on/off screen. Apparently it was so disconcerting to the audience that some of them got headaches from having to shift their focus so often
Click to expand...

If you remember where you read it I'd be interested in knowing.

My thinking was, if you could create acurate 3D spatial sound recreation you could actually break the frame and block the actors in 360 degrees round the camera, so as well as what was happening in front of the camera, you'd also be able to hear what was happening in the rest of the location. I can see your point about how that might be disconcerting for the audience and also how the sound track might get cluttered. Those are both good points. I still think it's worth playing with.
 
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Hi to All,

I just trawled the net on binaural recording and hit this thread. I am a binaural sound artist, who occasionally makes films with binaural sound - just as indicated above, that is in ear binaural microphones and carrying a camera (Panasonic NV500 or Canon HV20)

My work is very 'experimental', and I actually find it quite difficult to create _film_ with binaural sound as I am really an environmental sound artist.

'Canalisation 2' was filmed along the side of a canal at night in Nottingham, using sound improvisation with found objects and surfaces.

'Roundabout Improvisation' was filmed in Northampton market square at night with binaural sound and features a walkabout and sonic improvisation with an abandoned fairground roundabout. There is a clip on Youtube, but unfortunately the sound is MONO, and consequently not binaural. Also the image should be 16:9, not 4:3!

http://www.youtube.com/watch?v=8gBHw19rBz0

There is a music video I was involved in with binaural sound here:

www.swimmingband.com

If any members would like to collaborate on this in the UK, or on a wider scale, please contact me.

dallas.
 
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I'd be interested in how you map the binuaural for film in post production... the limitation has always been the difficulty in recreating the recorded sound from speakers.

I'd really appreciate knowing how you approach the whole workflow.
 
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As I said I'm not really a film guy, however...

A critical component of headphone (and speaker) binaural is spatial choreography - the movement of sound in 3 dimensional space. In my case it is created at the recording stage by sampling my own ears.

This can be done pre-filming, during filming or post filming.

Referring to the videos cited above, Canalisation 2 was performed and recorded to audio without filming, then 24 hours later the binaural soundtrack was played back over cans and the filming done cueing from the audio. (this was essential as I was the originating artist and wanted total control of audio performance and video filming). This was very much a conceptual artwork, hence the approach adopted. The audio was hand synced to video in post.

Roundabout Improvisation was filmed and recorded simultaneously to video and binaural. The binaural audio was hand synced to picture in post, cueing from the video camera sound. (Timecode would be useful - but is expensive)

The tricky part is scoring the spatial choreography. In the Swimming video there were two takes. One where the vocalist of the band physically led me around a multi speaker rig with speakers on the ground and fixed up trees to capture the spatial mix he required.

The second take i had free reign to make up my own spatial choreography to the playback. It was this second take featured in the video.

But there remains the issue of accurately mapping a spatial choreography in sound by some form of scoring or other instruction set. I'm willing to experiment here, but currently have no projects on the go...

best wishes,

dallas.
 
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Re Binaural Sound From Speakers.

Binaural is really a dedicated headphone presentation medium and I normally use headphone distribution amps (Behringer HA8000) at a venue where the audience can plug in their own headphones / earphones to extension leads wired into the performance venue.

The two speaker options are

1) the 'giant headphones' approach, where the two speakers are placed at 180 degrees either side of the audience, Or

2) crosstalk cancellation, with bipolar speakers, that is two speakers about 20cm apart and crosstalk cancelling applied to the audio. However this approach only reveals the full surround binaural when the listener is exactly on axis in front of the speakers.

With hi end audiophile speakers having a very accurate phase match a good proportion of the spatial information is retained on standard stereo speaker presentation, (or by using the left right pair of a 5.1 rig), with some phasing on moving sound sources.

Hope this is helpful.

Personally I think there is a lot of scope for dedicated headphone only presentations in small venues.

I'm actually performing binaurally with the band Swimming in Nottingham at the end of May in the basement at Lee Rosy's tea rooms. We will have a headphone installation for the audience upstairs, as well as a head camera for me and a stage camera, both of which will be video projected to the audience upstairs also.
 
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Thanks for explaining your process... I've been looking at the possibilities of mapping the binaural stereo pair into a 5.1 speaker environment and am looking at some VST devices that may allow me to map spacial nature of binaural into a standard cinema space.

If I make any progress, I'll add to this thread.
 
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Soundfield??

Moving slightly off topic, I wonder whether Soundfield surround sound may deliver the surround results you require better on 5.1 speakers?

In addition, a full spherical speaker rig with B Format can be impressive in respect of surround ambience, although the spacial (spatial?) definition with first order B format is very 'broad brushstrokes', ie big and wide!

(I do have a Soundfield Mk V in my studio)

Then there's the Holophone...

Best wishes.
 
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Sound field look very, very interesting... thanks a lot for that. I'm going to do a lot of reading about them and the audio workflow.

One of the reasons binaural appealed to me, was because binaural mics are pretty cheap... in fact you can simulate it with two cheap plate mics and an acoustic tile.

What I wanted was to see if I could "break the frame" in drama... so that the spatial information in the audio would allow the audience to feel as though they were sitting in the middle of the action. With some of the drama taking place outside the frame.

In other words.. the audience sense that the actors are behind them.

The other strand to this, is using equipment that any indie can afford to use!

If you've any ideas on how to accomplish that, I'd be very interested.
 
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In other words.. the audience sense that the actors are behind them.

The other strand to this, is using equipment that any indie can afford to use!

If you've any ideas on how to accomplish that, I'd be very interested.
__________________

The immersive element can be achieved to some extent by mixing dialogue and foley to surround, although the spatial definition is not sharp to the rear in a 5.1 rig, unless panned to specific speakers. So you have a frontal narrative with the video image and other dialogue 'off screen' mixed to the rear speakers, or panned to the sides.

With Soundfield B format recording the 4 track (B Format) master can be rematrixed to 5.1 0r, more excitingly, a multispeaker surround rig with height, allowing for up to 32 speakers.

So by recording in 4 channel B format you have all the surround spatial information to post prod into any surround speaker configuration. And there are B Format to binaural conversions available.

But always remember that Soundfield B format is big and wide, excellent for surrounding ambience, but not for pin sharp localisation, which is where headphone binaural wins hands down.

You can mix mono dialogue into a surround mix, which may give a sharper spatial presentation, but as always - experiment.

As for equipment and costs, its always a big issue!!!

Cheers,
dallas.
 
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