An improved method of generating audible alarms has been invented for stressful environments in which there may be consid- erable background noise and where the intended recipients of the alarms also need to pay att- ention to sounds other than the alarms. An aircraft cockpit is a typical example of such an environment. This method does not rely on a sustained loud alarm to attract attention because a loud alarm can be gratuitously startling and can mask other sounds that also demand attention. Instead, this method comprises the following elements: (1) The initial alert and subsequent reminders are given via short bursts of synthesized stereophonic signals with a spectrum sufficiently distinct from the noise spectrum to be noticeable. (2) Using pairs of earphones or loudspeakers to implement the stereophony, the alarm signal is made to appear to rapidly alternate between arrival from two different directions. (3) The alarm signal can be supplemented via stereophonic manipulation of background- noise signals.

This work was done by Durand R. Begault of Ames Research Center.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
Ames Research Center
(650) 604-5104.

Refer to ARC-14556.