This is a two-year proof-of-concept study to evaluate a new Virtual Reality (VR) "holographic" sound system for use as an audiological Orientation and Mobility (O&M) training tool

This is a two-year proof-of-concept study to evaluate a new Virtual Reality (VR) "holographic" sound system for use as an audiological Orientation and Mobility (O&M) training tool. This new system avoids the limitations of other technologies (i.e., binaural recordings and existing VR sound systems) that have been employed with limited success for audiological training. Four advancements in the state-of-the-art represented by this new holographic system provide new promise for audiological O&M training. First, unlike binaural systems, the new system allows the person to move their head in a natural fashion to localize sounds. Second, a spherical microphone array is used to record sound environments so as to retain the direction from which each ambient sound originated. When these recorded sound environments are later presented through head-tracking headphones in a VR environment, real-time software maintains the directionality of the sound so that it remains true no matter how the person moves or turns their head. Third, this new system models the actual physical acoustic structure of each person's head and ears to present sounds as they would be heard by that particular person in the recorded setting. Fourth, this system uses software algorithms to isolate specific sounds (i.e., of a moving vehicle) so that during virtual playback, these sounds can be inserted into the virtual sound field at will and in a customizable fashion to create truly unique and flexible virtual sound presentations.

There are two study hypotheses. First, when using sounds to negotiate traffic intersections, skills employed by experienced travelers in real environments will readily transfer to the proposed VR environment to the extent that audiological tasks performed in real environments are just as easily performed in the VR environment. Second, when the VR environment is enhanced to emphasize critical sound cues and eliminate distracting or confusing noises and sounds, performance by skilled travelers in the VR environment will be significantly better than in the actual environment.

The objectives are to: (1) adapt the existing spherical microphone array and digital recording software algorithms to best suit the capture of critical intersection sounds used for intersection negotiations; (2) develop software algorithms to deconstruct intersection sounds, isolating each sound for the VR construction of specific environments of varying complexity; (3) determine the level of sound detail necessary for negotiating intersections successfully; (4) expand the existing system to obtain the desired level of detail; (5) develop software to provide the ability to control the relative emphasis of a variety of sound elements being presented so as to simplify the auditory task; and (6) employ study participants to compare performance in the VR environment with outdoor performance.

Once validated, this system should be able to: (1) leverage instructor time by providing students with an effective means of practicing audiological skills on their own, (2) provide instructors with a means of introducing concepts in a graduated learning sequence that is not dependent on the happenstance availability of specific sounds and conditions found in real environments, and (3) provide audiological training for environments not located in the vicinity of the training site, but which do represent the veteran's home community.

Research will be conducted in collaboration with investigators in the Perceptual Interfaces and Reality Laboratory (PIRL) at the University of Maryland who initially conceived and developed this holographic VR sound system.

COMPARISONS: Outdoor O&M training exclusively

Inclusion Criteria:

• Must have little or no light perception
• OMCT (Orientation-Memory Concentration Test) of 10 or less
• Must have been independently and regularly crossing busy intersections for at least 3 years
• Ambulatory and able to walk for at least 10 minutes at a time without resting
• Auditory function at 25 db HL

Exclusion Criteria:

• Imbalance between ears - HL difference of 20 db HL or more

Early termination leading to small numbers of subjects analyzed. Technical problems with Virtual Sound System. None of the first 4 Subjects could distinguish between sounds in front versus sounds beside them.