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Accurate capture and reproduction of sound space
Amongst realistic sound systems, the 5.1ch surround sound system is the one usually sold.
However, it does not faithfully reproduce the captured sound, but uses a human psychological
illusion to play back a seamingly realistic sound space. In this laboratory, by faithfully reproducing
the captured soundspace, we aim to realize a more realistic acoustic system, and as part of this we
are currently studying SENZI and higher order ambisonics.
≪ Classification of 3D Sound Space Capture and Reproduction Systems ≫
| Classification |
Description |
| Multichannel acoustics |
Method reproducing the sound from one direction using a speaker resonating from this direction
(Examples: 5.1ch surround sound，22.2ch multichannel surround sound) |
| Binaural - transaural recording reproduction |
Methods for controlling the sound pressure in the eardrum
(Examples: transfer function synthesis, recording using dummy heads) |
| Sound field reproduction technology |
Method for controlling sound pressure in a specific region
(Examples: wavefront synthesis, higher order ambisonics) |
SENZI
Humans use only the input from their two ears to estimate the provenance, reverberation or differences
in height of sound. This means that reversibly, if you faithfully reproduce the sound coming to your ear
, you can make three-dimensional sounds heard with simple equipment such as headphones. SENZI is a
microphone array technology made of a high number of microphones installed in an environment
you want to record. It transmits the recorded sound information to a remote place and faithfully
reproduces this sound's direction, reverberation, height etc. for many listeners. We are currently
developing a prototype system that constitutes a spherical microphone array, records sound space using
252 microphones and reproduces the appropriate sound space information corresponding to the head movement
of the listener.
In order to physically reproduce sound space, it is necessary to measure the sound pressure coming
from every direction. However, data manipulation then becomes difficult. By using higher order ambisonics,
and expressing the captured sound space with a function called spherical harmonic function, it becomes
possible to playback sound space with great precision. However, there is a condtion : the speakers must be
placed spherically. In this laboratory, we are doing research to realize highly accurate sound space
reproduction even with non-spherical speaker arrangements. In addition, to demonstrate this, we have
constructed a sound space reproduction system that realizes 4th order ambisonics using 32ch speaker array.
Figure : Higher order ambisonics sound space reproduction
Figure : 32ch sound space reproduction system
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