BILOCATION - BINAURAL RECORDING

If a stereo recording is made, using a pair of microphones spaced apart so as to imitate the human ears (with a baffle in between) an awful lot of complex spatial information will also be recorded. When played back on headphones, the technique can give vivid impressions of space: producings sounds that appear to come from all around the head, and from above and behind it. Some recordists use a 'dummy head' - a model of a human head with mics fixed to, or inside it. Others use their own head, and either attach mics near their ears (eg to a pair of glasses) or in some cases the mics ar fitted inside the ears. Perfectly good results can be obtained by spacing two mics 6" apart and putting a sound-absorbing baffle (like a rolled-up towel) between them.

The spacing of the mics, and the 'sound shadow' cast by the head, produce auditory cues that the brain decodes into spatial information that can be uncannily accurate. A recording played back in the same room as it was recorded in, can be very scary! If someone speaks behind the head on the recording, for instance, the listener will usually turn to answer someone who's no longer there!

The mics should ideally be uni-directional, which happily is usually the case with cheap tie-clip mics - easily obtainable from Maplin or Radio Shack. There's much more detailed information on all of this in the Sound on Sound article about the making of Bilocation.

 

Copyright © 2005 Steve Marshall.