Virtual Acoustic Enhancement of Traffic Collision Avoidance System Advisorie
Principal Investigators
Elizabeth Wenzel, Durand R. Begault
Abstract
Research has been ongoing at the Spatial Auditory Display Laboratory at NASA Ames Research Center in the area of "head-up auditory displays" for enhancing commercial aviation safety. Similar to a head-up visual display, the use of 3-dimensional audio cues allows a pilot to keep their visual gaze out-the-window "head-up" while simultaneously receiving situational awareness information of a spatial nature. The 3-dimensional audio cues are imposed on speech signal messages that are delivered to each pilot via active noise-cancellation headphones.
Ten commercial airline crews were evaluated in a flight simulator study to determine whether the existing Traffic alert and Collision Avoidance System (TCAS) could be improved by including 3-dimesnional audio cues with the head-down map display system currently in use. The experimental condition had the verbal "traffic traffic" alert for the TCAS advisory processed so its perceived lateral spatial location corresponded to the location of aircraft traffic ("targets") seen out of the windshield; a control condition used the standard TCAS system. Ten crews participated in a within-subjects design, flying a route from San Francisco to Los Angeles with 49 targets.
Results indicated a significant difference for target acquisition time favoring the 3-dimensional audio TCAS condition by 307 ms on average. The maximum advantage for 3-dimesional audio was 493 ms on average for peripheral targets at ±48° relative azimuth. There was no significant difference in the number of targets acquired. Figure 1 gives a summary of the data as a function of target location.
Overall, the advantages of implementing a 3-D audio display to augment existing TCAS systems can be seen. The concept of augmenting the existing TCAS system with 3-D audio cues, rather than building a new display system from the "ground up," is both unique and likely inexpensive to implement. It appears that the integration of 2-channel binaural sound into the cockpit would offer safety benefits to the aviation community in line with other mechanisms for enhancing situational awareness.
