Shape Recognition With Sounds: Improvement in Sighted Individuals After Audio–Motor Training

Abstract

Recent studies have demonstrated that audition used to complement or substitute visual feedback is effective in conveying spatial information, e.g., sighted individuals can understand the curvature of a shape when solely auditory input is provided. Recently we also demonstrated that, in the absence of vision, auditory feedback of body movements can enhance spatial perception in visually impaired adults and children. In the present study, we assessed whether sighted adults can also improve their spatial abilities related to shape recognition with an audio-motor training based on the idea that the coupling of auditory and motor information can further refine the representation of space when vision is missing. Auditory shape recognition was assessed in 22 blindfolded sighted adults with an auditory task requiring participants to identify four shapes by means of the sound conveyed through a set of consecutive loudspeakers embedded on a fixed two-dimensional vertical array. We divided participants into two groups of 11 adults each, performing a training session in two different modalities: active audio-motor training (experimental group) and passive auditory training (control group). The audio-motor training consisted in the reproduction of specific movements with the arm by relying on the sound produced by an auditory source positioned on the wrist of participants. Results showed that sighted individuals improved the recognition of auditory shapes only after active training, suggesting that audio-motor feedback can be an effective tool to enhance spatial representation when visual information is lacking.

The Topo-Speech sensory substitution system as a method of conveying spatial information to the blind and vision impaired

“…This question is particularly interesting with relation to tasks in which vision is classically thought to play a central role, for example, spatial perception. On the one hand, it was commonly accepted that the blind and visually impaired have a significant impairment with respect to their sense of space and capability for forming spatial representations ( Gori et al, 2014 ; Cappagli et al, 2017b ; Martolini et al, 2020a ). However, research now indicates that following dedicated training, the blind can become more capable of spatial localization ( Gaunet et al, 1997 ; Cappagli et al, 2017a ).…”

“…A previous study showed that individuals with low residual vision (peripheral) were less capable of sound localization and performed worse than both their blind and sighted counterparts ( Lessard et al, 1998 ). Another study showed that children with visual impairments are less capable of updating spatial coordinates as compared to the sighted ( Martolini et al, 2020a ). It could be that in the case of the visually impaired, compensatory neuroplasticity takes place to a lesser extent than in the blind, and yet their vision is severely impaired in comparison to the sighted.…”

“…It has been suggested ( Röder et al, 2004 ) that when vision is unavailable, the following three scenarios are possible: The first scenario posits that there will be a lack or decrease in the sensory capabilities due to the lack of an essential sense (vision) ( Gori et al, 2014 ; Cappagli et al, 2017b ; Martolini et al, 2020a ). The second is that no difference will be observed ( Haber et al, 1993 ; Morrongiello et al, 1995 ).…”

How much I moved: Robust biases in self-rotation perception

“…For instance, a previous study that used sound level discrimination and auditory detection tasks (Myers et al, 2020 ) showed that sensorimotor integration may improve the accuracy of the perception of self-generated sounds. Along these lines, in the rehabilitation domain, the association between active body movements and auditory stimuli allows participants to build accurate spatial representations after 30 min of training (Martolini et al, 2020 ). A previous study about spatial auditory memory (Setti et al, 2018 ) showed a significant influence of active exploration in memorizing the spatial organization of a virtual semantic acoustic scene.…”