How do people with vision loss judge distances of sound sources?

Abstract

Purpose : Vision loss can lead to enhancement of some auditory abilities, and deficits in others. What is not yet known is whether these changes are related to the severity of sight loss. This study examines whether distance estimates for sound sources are dependent on the type of task and/or to the magnitude of sight loss. It is also largely unknown how echoes (reverberation) influence these judgements.

Methods : Sixty participants with different levels of vision loss took part. A virtual room using sophisticated virtualization software simulated sound sources that were presented at various distances. Sound distance cues including the loudness (level) of the sound source and direct-to-reverberant ratio (echoes) were experimentally manipulated within the virtual room. All participants were audiometrically tested and had normal hearing. Static sound stimuli at virtual distances ranging from 1.2 to 13.8 m. were presented. Three different types of stimuli: Single speech, music, or noise sounds were presented. Participants estimated the distance of the sound source, and also the size of the virtual room. Data were compared to age matched sighted controls.

Results : For sighted controls, distance estimates were most accurate for closer sounds and least accurate for farther sounds (p<0.05). Participants with severe visual losses perceived sounds to be twice as far away, and rooms to be three times larger compared to sighted controls (p<0.05). With increasing severity of vision loss, distance accuracy decreased for closer sounds and increased for farther sounds. More severe visual loss was associated with more accurate room size estimates in rooms with reverberation (echoes). <!--0.05).-->

Conclusions : The results demonstrate that cross modal calibration of audition by vision is influenced by the severity of visual loss. The results have important clinical implications for participants with vision loss as they are less accurate at judging distances of closer sounds which are important for many activities of daily living, for example when negotiating a safe path to avoid collisions with other people, and falls.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.