Evaluation of acoustic beacon characteristics for navigation tasks

Abstract

The goal of the present study was to investigate the human factors issues related to acoustic beacons used for auditory navigation. Specific issues addressed were: (1) the effect of various beacon characteristics on human accuracy in turning toward the direction of the acoustic beacon; (2) the difference between real and virtual environments on human accuracy in turning toward the acoustic beacon; and (3) the perceived sound quality of various acoustic beacons. Three experiments were conducted in which acoustic beacons were presented in a background of 80 dBA pink noise. Results of the localization tasks revealed that (a) presentation mode (continuous versus pulsed beacon sound) did not affect the overall localization accuracy or number of front-back confusion errors; and (b) the type of acoustic beacon affected the size of localization error. Results of the sound quality assessment indicated that listeners had definite preferences regarding the type of sound being used as a beacon, with (a) non-speech beacons preferred over speech beacons, (b) a beacon repetition rate of 1.1 rps preferred over either the 0.7 or 2.5 rps rates, and (c) a continuous operation of a beacon preferred over a pulsed operation. Finally, sound quality ratings and localization errors were highly negatively correlated. This finding demonstrates the usefulness and practical values of sound quality judgements for audio display design and evaluation.

Navigation Performance With a Virtual Auditory Display: Effects of Beacon Sound, Capture Radius, and Practice

“…Once the user reaches the waypoint indicated by the beacon, the sound shifts to represent the location of the next waypoint, the user reorients, and then the user sets off on the next path segment. As pointed out, Tran et al (2000) reported that specific sounds can lead to better localization and thus better performance in this sort of task.…”

“…Speech beacons are harder to localize in a virtual environment than are nonspeech beacons (Tran, Letowski, & Abouchacra, 2000). Users also give speech beacons low ratings for quality and acceptance (Tran et al, 2000). The speech-based interface cannot display a large amount of information, as two or more speech beacons presented simultaneously are difficult to attend to, given the limited human speech-processing capacity (e.g., Mowbray, 1953;Mowbray & Gebhard, 1961).…”

“…Only recently have researchers begun to study nonspeech sounds that can be used in this sort of system. Tran et al (2000) investigated the effect of sound characteristics on localization and subsequent navigation, the effect of real environments compared with virtual acoustic environments, and the qualitative aspects of various types of acoustic beacons. They summarized their findings by suggesting that the sounds should be wideband and nonspeech, with a proper balance between low-and high-frequency energy to make it pleasant and easy to localize.…”

Gender differences in spatial perception of body tilt

“…According to their study, simple waveforms, such as sine waves, produce the best acoustic beacon, whereas complex ones, such as speech, produce poorer beacons. These studies also indicate that auditory distances are harder to estimate accurately than are visual ones, in part due to acoustic parameters being more variable than light-based ones (Bronkhorst & Houtgast, 1999;King, Schnupp, & Doubell, 2001;Mershon et al, 1989;Tran et al, 2000). These studies support the impact of auditory information on the perception of space and suggest that acoustic information may well contribute to the perception of body tilt.…”

“…These findings demonstrated that when room reflectance is low, perceived distance is underestimated and that when room reflectance is high, perceived distance is overestimated. Tran, Letowski, and Abouchacra (2000) demonstrated that localization error is influenced by the type of sound used as a beacon. According to their study, simple waveforms, such as sine waves, produce the best acoustic beacon, whereas complex ones, such as speech, produce poorer beacons.…”