Virtual Environments - SPIN and Sound Spatialisation

The aim of new developments is to integrate sound spatialisation hardware with the spin interface and hence enhance the users environmental immersion. The spin environment offers a unique visual immersion in which the individuals entire peripheral vision is enveloped by the virtual space. Currently the acoustic environment in spin does not match this state of visual immersion. It is therefor the goal of these developments to add another layer of complex sensorial input and therefore provide a more cohesive environment.

The first question posed was how to create a multichannel sound environment suited to the spin interface. The conventional approaches to spatial sound via the use of speaker arrays are not feasible in this instance as the spin sphere acts as a 3 meter acoustic isolation chamber. This subsequently would inhibit the transmission of nearly all acoustic energy from outside the sphere and quite obviously speaker arrays are not possible inside the interface itself.The most suited approach was to utilize the stereo wireless headphone system currently in operation with the spin interface. The existing audio environment could then be modified with the use of binaural signal processing.

Binaural processing simulates how sound is spatially perceived by an individual. This is achieved by utilizing head related transfer functions (HRTF’s). Lake Technology, whom have supported these developments, have provided highly accurate real-time headphone spatialisation hardware that will enable up to 16 channels of sound to be positioned simultaneously with very low latency. The CP4 hardware/ software utilized has the capability of providing up to 32 simultaneous sources of binaural encoding. Due to both the nature of the spin environments and human auditory perception substantially less than this should be required for a successful outcome with a single user.

The addition of headtracking hardware is necessary to enable the sound engine respond to individuals head movements within the space and to subsequently modify the acoustic environments accurately. Without this addition only a partial sense of sonic immersion would be achieved. As with all other data transmission from within the spin environment the headtracking hardware will have to be modified to function as a wireless device.

The aim of this added sonic complexity is not only to enhance the realism of current environments but to also facilitate exploration into more unconventional virtual environments and scenario’s. The common simulation of relatively tangible Euclidean spaces may give way to more abstract spaces in the form of non-spaces and sound only environments without the same emphasis on visual stimuli. The sonic environments develops for SPIN would also provide a platform for further ongoing investigations into the bioeffects of sound on individuals and the use of sound to manipulate humans psycho-physiological states. Sound could subsequently be utilized within the Body SPIN framework to directly manipulate the individual and hence modify their immediate environment.
ad sept 2001

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