Fancy a Bit of Binaural? By Ross Burman (WTC Editor)

Ears are funny things.  Look at them, go on, look:  Little bits of gristle flapping in the wind.  Surely they can’t be there for decoration?  That would remove all doubt against the existence of an omnipotent and omniscient God.  Actually, the pinnae (as they are known) are highly evolved sound processors, focussing and transmogrifying sound as it hits your ears.  Like wine in the mouth of a sommelier, sound is washed around the ridges and folds of the outer ear.  It is then directed down the ear canal to the ear drum, vibrating the hammer, anvil and stirrup (the smallest bones in the human body) which in turn transmit information to the cochlea which finally translates the sounds for the brain.  

The result of this premixing by the pinnae is that the sound fired into the holes on either side of the head have all manner of directional information encoded into it.  Close your eyes for a second and have someone click their fingers around your head.  Thanks to those ear flaps you’ll be able to pinpoint the whereabouts of the clicks.  

You are immersed in a world of sound.  Binaural attempts to replicate this. 

Now, your normal, everyday stereo reproduction requires you to use your own pinnae to locate sounds from two speakers some distance away.  The upshot of this is similar to going to the cinema:  a flat image projected in front of you, the audience, sitting in a darkened room.  You are separated from the action, a detached observer.  Binaural recording, by contrast, drops you in the middle of the action by feeding sound, already ‘pinnae-encoded’ directly into the ear canal.  This is why binaural recordings should only be listened to on headphones, bypassing your own pinnae. 

Well, that’s all very well, but how are these recordings made?  Normally for radio drama, a couple of microphones (one for each stereo channel) are set up and the actors play to these as if they were the audience.  With binaural recording, the microphones are setup so each acts as an ear canal.  Sometimes these mics are affixed to a real head (an actor in the play) or to a dummy head the same size and density as a human head (‘want to lose twelve pounds of unsightly fat?’  once asked David Frost, ‘then cut off your own head!’).  This dummy head also, importantly, has its own pinnae. 

But wait a minute, because with a binaural recording you are listening to post-pinnae-encoded information.  It’s not your ears you’re hearing through.  It’s not even your head.  When you are listening to a binaural play, you’re not just ‘in’ the play; you’re inhabiting someone’s head. 

Hold that thought while you’re listening to Gareth Parker’s ‘Autopsy’.

~ by wirelesstc on April 18, 2011.

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