Janet M. Weisenberger

The sense of presence for the suddenly deafened adult: Implications for virtual environments

Reports from adventitiously deafened individuals of a sense of unconnectedness with their surroundings, of a sense that the world seems dead, offer a compelling rationale for the argument that auditory cues are a crucial determinant of the sense of presence. Moreover, the crucial element of auditory stimulation for creating a sense of presence may be the auditory background, comprising the incidental sounds made by objects in the environment, rather than the communication and warning signals that typically capture our attention. Although designers of virtual environments have most often tried to maximize the sense of presence in the user by attempting to improve the fidelity of visual displays, the arguments presented here suggest that background auditory stimulation may be useful or even critical for achieving a full sense of presence.

Multisensory roughness perception of virtual surfaces: effects of correlated cues

Previous studies of multisensory texture perception have addressed the relative contributions of different modalities, examining visual/haptic and auditory/haptic interactions. In the present study, the ability of observers to use information from three sensory modalities (visual, auditory, and haptic) was examined in a virtual texture discrimination task. Results indicated better performance for two- and three-modality conditions for some stimuli but not for others, suggesting that the interactions of haptic, auditory, and visual inputs are complex and dependent on the specifics of the stimulus condition. Viewed in this manner, the results are consistent with the modality appropriateness hypothesis. These findings are discussed in view of current formulations of multisensory interaction.

The role of multisensory feedback in haptic surface perception

In performing most everyday tasks, we use information from several different sensory modalities, yet our understanding of how these inputs are integrated is limited. The present study investigated the role of multisensory feedback in the perception of surface roughness, specifically focusing on whether the threshold for distinguishing the roughness of two virtual surfaces was different under visual + haptic conditions, as compared to visual-only or haptic-only conditions. Haptic stimuli were presented via the PHANToM; visual stimuli were presented via computer monitor. The virtual surfaces were sinusoidal gratings that varied in spatial period across trials. Overall, results suggested that threshold was determined by haptic input at low surface amplitudes, and by visual input at high surface amplitudes. At intermediate amplitude values, it appeared that observers were combining information across modalities to produce a percept in the combined condition that was better than that obtained under either single modality condition.

Masker fringe and binaural detection

Yost [J. Acoust. Soc. Am. 78,901-907 (1985)] found that the detectability of a 30-ms dichotic signal (S pi) in a 30-ms diotic noise (No) was not affected by the presence of a 500-ms dichotic forward fringe (N pi). Kollmeier and Gilkey [J. Acoust. Soc. Am. 87, 1709-1719, (1990)] performed a somewhat different experiment and varied the onset time of a 25-ms S pi signal in a 750-ms noise that switched, after 375-ms, from N pi to No. In contrast to Yost, they found that the N pi segment of the noise reduced the detectability of the signal even when the signal was temporally delayed well into the No segment of the noise and suggested that the N pi segment of noise acted as a forward masker. To resolve this apparent conflict, the present study investigated the detectability of a brief S pi signal in the presence of an No masker of the same duration as the signal. The masker was preceded by quiet or an N pi forward fringe and followed by quiet, an No, or N pi backward fringe. The present study differs from most previous studies of the effects of the masker fringe in that the onset time of the signal was systematically varied to examine how masking changes during the time course of the complex fringe-masker-fringe stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of a Collaborative Movement Task in a Distributed Three-Dimensional Virtual Environment

A task designed to estimate the impact of communication channel performance on individual and collaborative human performance in distributed, shared, virtual environments was evaluated. The Fitts-like task required participants to press buttons as fast as they could in a three-dimensional virtual workspace. In addition, in the collaborative task the 2 participants were required to press the buttons simultaneously. The size of the buttons, the distance between buttons, and the delay between movement and visual feedback were manipulated. The results were well described by Fitts law. Movement Time increased with increases in Index of Difficulty and delay. The Index of Performance decreased with delay and was lower in the collaborative task. Overall, orderly changes in performance were observed with manipulation of task parameters, suggesting that future studies to examine more complicated manipulations of network performance and multisensory displays are appropriate.

Audition and the sense of presence in virtual environments

Historical reports from suddenly deafened adults describing a sense of detachment from a world devoid of auditory input suggest that auditory cues may be crucial for achieving a sense of presence in virtual environments [R. H. Gilkey and J. M. Weisenberger, Presence 4, 357–363 (1995)]. However, factors other than acoustic fidelity can affect the perceived quality of a virtual auditory display. For example, Simpson et al. [J. Acoust. Soc. Am. 100, 2633(A) (1996)] showed that the sense of presence in virtual auditory environments was driven by characteristics of the real listening environment in which the virtual audio was heard. Specifically, when the virtual auditory environment matches the real listening environment, the listening experience is particularly compelling. However, it was not clear whether auditory or visual experience with the real room mediated this effect. This paper describes attempts to separate the impact of auditory and visual information on presence by systematically manipulating the...

Issues in evaluating wearable multichannel tactile aids

The viability of the tactile system to convey information about speech sounds to hearing‐impaired persons has been substantiated in a number of laboratory studies. In particular, the addition of multichannel tactile devices to lipreading can provide considerable additional information in speech perception tasks, as compared to lipreading alone. Further, studies of Tadoma have demonstrated the ability of the tactile system to transmit speech information even in the absence of visual input. The recent introduction of a number of wearable multichannel tactile devices has made it possible to extend the findings from laboratory studies into everyday clinical and educational settings. A number of factors must be considered in attempting to obtain results from these wearable devices in nonlaboratory settings that will equal or even surpass findings from laboratory studies. These include the level of background noise in the environment, the number of channels and speech processing strategy of the device, the natu...