Business & GA, Military

Editor’s Note: Introducing 3D Audio

By Charlotte Adams | March 1, 2006
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The military research establishment over the years has developed technologies that have made a difference in the civilian world. Just think of GPS. The laboratories still pursue potentially dual-use innovations, as we report in this issue of Avionics Magazine. The Q&A feature updates readers–or, more likely, introduces them–to a technology known as 3D audio.

Unlike some military research, 3D audio and its applications are immediately comprehensible. Untrained participants in 3D audio experiments seem to understand it quickly. The technology could complement visual cockpit displays and improve safety and human performance in the flightdeck.

This technology allows sounds to be heard through a stereo headset as if they came from different locations around the listener. Sounds can be further distinguished from each other by manipulating pitch, harmonics and volume. This localization feature, for example, can help communications officers comprehend the content of multiple radio channels by drawing on the same skills a guest at a cocktail party uses to scan conversations around a room.

The concept of 3D audio is not new, but scientists in the Human Effectiveness Directorate of the U.S. Air Force Research Laboratory (AFRL), Wright-Patterson AFB, Ohio, have evolved a software-based approach that makes the technology more practical and affordable. They also have developed novel auditory cues regarding distance from an object or waypoint and the proper heading to get there.

So far only one 3D audio application is "live" in the U.S. Air Force. Air traffic controllers at Nellis AFB in Nevada are using the technology to monitor aircraft communications during exercises at the facility’s test range.

Another 3D audio application–the "auditory horizon"–has garnered congressional interest as a potential general aviation (GA) safety aid. In demos this "auditory display" uses music played into the pilot’s headset. When an aircraft departs from straight and level flight, the music changes to indicate the required corrective maneuver. When the aircraft pitches down, for example, the music sounds a little higher in frequency. If the aircraft rolls to the left, the music sounds a little louder in the artificial space to the right of the pilot. The technology filters the sounds, but the music remains enjoyable, so that the pilot continues to listen to it.

Students at the Test Pilot School, Edwards AFB, Calif., flew a C-12 training aircraft, using the auditory horizon. Although GA is the lab’s primary focus, the warning system could benefit military pilots, too, as they receive initial flight instruction in GA aircraft. NASA Langley also sees potential in 3D audio technology, according to Bob Lee, chief of the Battlespace Acoustics Branch at AFRL’s Human Effectiveness Directorate. At press time, NASA planned to make a Cirrus SR22X aircraft available for AFRL flight tests over several weeks in March, according to an agency spokeswoman. AFRL will supply the 3D audio equipment and NASA will provide subject pilots and safety pilots. The agency, however, does not anticipate further research involvement in 3D audio at this time, she says.

If budgets permit, AFRL also may demonstrate the technology as part of a new digital intercom system for E-3 command and control aircraft.

Lee is quick to emphasize that 3D audio would complement, not replace, visual displays in the cockpit. "That’s a key point," he says. "When everything works together, you don’t get disoriented."

Pseudo-3D depictions are being designed into cockpits to make complex displays easier to comprehend. In extreme situations, however, it may be difficult for the pilot to concentrate on a visual display. That’s when a timely, intuitive audio alert could make all the difference.

Although the military’s acquisition and requirements community has not fully embraced the technology, let’s hope NASA will become convinced of its value and pursue 3D audio for general aviation safety.

Another Introduction…

While we’re on the subject of introductions, I’d like to announce the addition of Andrew D. Parker, as the new managing editor of Avionics Magazine. Andrew comes to our publication from Professional Pilot magazine, where he served as associate editor. In addition to his aviation background, Andrew has experience as a reporter with weekly community newspapers.

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