Virtual Auditory Displays

Abstract : Auditory processing is often given minimal attention when designing virtual environments or simulations. This lack of attention is unfortunate since auditory cues play a crucial role in everyday life. Auditory cues increase awareness of surroundings, cue visual attention, and convey a variety of complex information without taxing the visual system. The entertainment industry has long recognized the importance of sound to create ambience and emotion, aspects that are often lacking in virtual environments. In short, placing someone in a virtual world with an improperly designed auditory interface is equivalent to creating a "virtual" hearing impairment for the user. Auditory perception, especially localization, is a complex phenomenon affected by physiology, expectation, and even the visual interface. Different methods for creating auditory interfaces will be considered. As will be discussed later in this chapter, spatialized audio using headphones is the only audio technique that is truly "virtual" since it reproduces azimuth, elevation, and distance and offers the sound engineer the greatest amount of control over the auditory experience of the listener. For many applications, especially using projections screens, speaker systems may be simpler to implement and provide benefits not available to headphone systems. Properly designed speaker systems incorporating subwoofers may contribute to emotional context. The positives and negatives associated with each option will be discussed. It is impossible to include everything that needs to be known about designing auditory interfaces in a single chapter . Instead of trying to review all perceptual and technical issues relevant to creating virtual auditory displays, this chapter unapologetically focuses on issues of spatial auditory perception and the generation of spatial auditory cues, since this area has undergone rapid development with the advent of virtual environments.