Redwood Neuroscience
Title "A New Method For Capturing and
Reproducing Spatial Sound "
CIPIC Interface Laboratory
Abstract:
The two standard methods for capturing live spatial
sound with microphone arrays attempt either to reconstruct the incoming wave
field or to reproduce the sound pressure at the eardrums. Commercial
surround-sound systems usually use loudspeakers to provide approximate wave
field synthesis, and the effect of the listener's head is automatically
accounted for by immersing the listener in the sound field. Unfortunately, exact wave field
reconstruction requires a very large number of channels. Binaural or dummy-head recordings, which need
only two channels, usually use headphones to provide separate signals directly
to the ears. Here the effect of the
listener's head is approximately accounted for by the corresponding dummy head.
Unfortunately, binaural recordings do not account for the dynamic effects that occur when listeners turn their heads, and the sonic world
turns whenever the listener turns.
We describe a new approach that exploits the strong
sound localization cues that are evoked by voluntary head motion. Our new method -- called MTB for Motion-Tracked
Binaural -- is a generalization of binaural recordings. It uses more than two
channels so that it can capture the dynamic effects generated by the listener's
motion and stabilize the acoustic field.
The result, which is best heard over headphones, is highly realistic reproduction
of spatial sound with modest bandwidth requirements. The method requires interpolation between
microphone signals, and the properties of different interpolation methods will
be presented and demonstrated.