3-D Audio: Military Applications and Symbology

Five experiments were conducted to study the acoustic attributes that enable the accurate identification and localization of rudimentary spatial warning sounds. In each experiment, two sounds were played simultaneously over loudspeakers at various azimuths and elevations. The stimuli consisted of pure tone complexes with a 13 kHz bandwidth. The fundamental frequencies, the amplitude modulation rate of the complex, the harmonicity of the carrier and modulation frequencies, and the coherence of the carrier and modulation phase were varied in the experiments. The combination of all the cues provided the best localization and identification performance. When and only when all cues were used, the subjects were able to accurately localize and identify the target sound.