Combat Aural Awareness System
A system of audio cues used by the Asari Republican Navy (see: Asari Republics), also known by its abbreviation CAAS. Civilians have erroneously referred to it as "symphonic tactical audio", which has given some people the impression that CAAS is battle music, which it is not.
CAAS has been developed and maintained by the Lafellana Joint Noetoware corporation. The Asari Republican Navy and several smaller independent asari navies utilize CAAS.
Use of CAAS
Combat information officers who are in charge of observing and interpreting accumulated sensor information on the bridge make use of CAAS. A specialized headset is used for this purpose to isolate noise.
The CAAS system uses various tones and sound clips to compress three variables into one sound byte that is then played to the CIO. These variables are ship class, direction and distance. Via this system a CIO can stay updated to placement of hostile vessels through their sense of hearing. A lone tone could indicate a cruiser-sized vessel straight ahead at moderate distance, or a burst of chirps could warn of wing of fighters approaching from the flank at close range.
The concept was initially mentioned by asari_promiscuity in this post but was not elaborated further, until this article was made.