An assessment of virtual auditory distance judgments among blind and sighted listeners

Abstract

Auditory distance perception is a crucial component of blind listeners′ spatial awareness. Many studies have reported supra-normal spatial auditory abilities among blind individuals, such as enhanced azimuthal localization (Voss et al., 2004) and distance discrimination (Kolarik et al., 2013). However, it is not known whether blind listeners are better able to use acoustic information to enhance judgments of distance to single sound sources, or whether lack of visual spatial cues prevents calibration of auditory distance information, leading to worse performance than for sighted listeners. Blind and sighted listeners were presented with single, stationary virtual sound sources between 1.2 and 13.8 m away in a virtual anechoic environment simulated using an image-source model. Stimuli were spoken sentences. Sighted listeners systematically underestimated distance to remote virtual sources, while blind listeners overestimated the distance to nearby virtual sources and underestimated it for remote virtual sources. The findings suggest that blind listeners are less accurate at judging absolute distance, and experience a compression of the auditory world, relative to sighted listeners. The results support a perceptual deficiency hypothesis for absolute distance judgments, suggesting that compensatory processes for audition do not develop among blind listeners when estimating the distance to single, stationary sound sources.

The accuracy of auditory spatial judgments in the visually impaired is dependent on sound source distance

“…Tactile feedback in peripersonal space might be used to calibrate audition as an alternative to vision 11 , and audiomotor feedback from the systematic changes in sound cues arising from the movement of the head and body has also been suggested as a means to calibrate internal representations of sound azimuth in the absence of vision 12 . In contrast to the relatively accurate localization performance for azimuth observed in blind individuals 9,42 , the current results for partially sighted participants are consistent with previous work reporting that absolute distance accuracy is worse for blind than for sighted controls in peripersonal space 16,17,57,58 . Taken together, these results suggest that if vision is absent or degraded, tactile feedback is insufficient to calibrate auditory distance in peripersonal space, corresponding to "near" space in the current results.…”

“…It is not yet known how severe the visual loss needs to be before significant alterations in auditory abilities are observed, or whether the relationship between severity of visual loss and changes in auditory abilities is systematic. If it is systematic, then people with more modest visual losses should exhibit smaller changes in auditory abilities than those with more severe visual losses.Previous work showed that compared to sighted controls, individuals with total vision loss estimate near sound sources to be farther away and estimate farther sound sources to be closer 16,17 , demonstrating the critical role that vision plays in calibrating auditory space 18 . A number of studies have also shown that partial visual deprivation affects auditory localization abilities.…”

“…Previous work showed that compared to sighted controls, individuals with total vision loss estimate near sound sources to be farther away and estimate farther sound sources to be closer 16,17 , demonstrating the critical role that vision plays in calibrating auditory space 18 . A number of studies have also shown that partial visual deprivation affects auditory localization abilities.…”

“…Stimuli were presented using Sennheiser HD219 headphones. The stimuli were generated using methods described in our previous studies 16,17,[31][32][33] . A virtual room measuring 35 m (length) x 30 m (width) x 10 m (height), that was either anechoic (where only sound level information about distance was available 24,28,34 ) or reverberant (where both level and echoic direct-to-reverberant energy ratio [DRR] distance cues were available 33,35,36 ), was generated using an image-source model (ISM) 37 .…”

Auditory and proprioceptive spatial impairments in blind children and adults

“…Sadato, Pascual-Leone, Grafman, Ibanez, Deiber et al, 1996;Weeks et al, 2000), and that even a few days of binocular deprivation is sufficient to reveal colonization of primary visual cortex by touch (Merabet, Hamilton, Schlaug, Swisher, Kiriakopoulos et al, 2008). On the other hand, it has recently been shown that blind people are impaired in auditory (Gori et al, 2014;Kolarik et al, 2013b;Lewald, 2002;Zwiers et al, 2001) and tactile tasks (Noordzij et al, 2007;Postma et al, 2008;Ungar et al, 1995). It has been hypothesized that these impairments reflect a lack of visual calibration over the other modalities in processing spatial information (Gori et al, 2014).…”