Early vision loss linked to challenges judging auditory distances
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Key takeaways:
- Participants with early-onset visual impairment exhibited significant changes in estimates of close and middle distances.
- No significant differences were reported between controls and late-onset VI participants.
Early-onset vision loss may be associated with difficulty judging auditory distance, particularly close and middle distances, according to research published in Optometry and Vision Science.
“The aim of the current study was to investigate whether age at onset (before 10 years and after) affected absolute auditory distance judgments in people with [visual impairment (VI)],” Shahina Pardhan, PhD, from the Vision and Eye Research Institute at Anglia Ruskin University, and colleagues wrote. “As previous studies reported that fully blind individuals with late-onset visual loss made spatial judgments similar to those for sighted controls for various tasks, it was hypothesized here that performance of judged distance would be greater for early-onset VI participants when compared with late-onset VI participants.”
The researchers assessed 52 participants, aged 33 years or younger, who were recruited from Sankara Nethralaya Eye Hospital in Chennai, India, and divided into three groups: normally sighted controls (n = 18), early-onset VI (n = 24) and late-onset VI (n =10). All participants had normal or near-normal hearing.
Participants were blindfolded and asked to verbally estimate the distance of a series of sounds played at a variety of distances, ranging from 1.2 meters to 13.8 meters, played in blocks of 80 trials. The stimulus types — speech, music or noise — and room conditions —anechoic or reverberant — remained constant within each block. Each participant performed 480 trials.
According to results, the normally sighted group had the most accurate judgements for close distance sounds, but underestimated distance with increasing source distance. Conversely, early-onset VI participants reported the farthest distance estimates, while late-onset VI participants provided estimates in between the other two groups. However, both VI groups overestimated distances of closer sound sources, which researchers reported was “consistent with previous findings for blind individuals.”
Overall, the early-onset VI group exhibited significant differences from sighted controls for closer distances in all conditions except anechoic speech and at middle distances for all conditions except reverberant speech and music; researchers reported no significant differences between the late-onset VI group and controls.
“Taken together, the results show that, in general, early partial visual loss but not late-onset visual loss leads to significant changes in auditory distance judgments,” Pardhan and colleagues wrote.
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