David Black, Tim Ziemer, Christian Rieder, Horst Hahn, Ron Kikinis.

Introduction: Navigation information for clinical applications using tracked instruments is typically shown on a screen in an operating room. Instruments, e.g., dissector, needle, or fraise, are viewed in relation to preoperative planning data. Although visual methods provide useful information, clinicians must remove their view from the patient to view monitors often placed in uncomfortable locations. Transmitting navigation cues using auditory display instead of a screen can benefit the clinician in numerous ways, foremost by allowing visual attention to remain on the patient while receiving useful information about the placement of a tracked tool.

Methods: This work presents two auditory display methods to supplement visual methods for placement of medical instruments in cognitively demanding tunnel-like navigation tasks, such as for needle placement, image-guided laparoscopy, or transnasal robotcs, where an instrument must be navigated to remain on the origin of a plane orthogonal to the line to a planned target. Two novel auditory displays for instrument guidance are described: first, a note-based synthesizer that employs glissando direction (pitch bending) and stereo mix, and second, a virtual choir of sung syllables that guide the clinician towards a planned path.

Results: Results of a first evaluation of users using a think-aloud usability show that both methods can provide complete screen-free guidance to guide towards a target inside a virtual 3d tunnel model of a transnasal passage. The work describes benefits and drawbacks each method, providing insight for future applications of auditory display for medical navigation.

Conclusion: The methods allow blind guidance but are intended for future use in hybrid audiovisual solutions to provide an optimal combination of in-depth visualization and quick, efficient auditory cues when the clinician needs them most, thus increasing usability of navigation aids.