Seeing Through Sound: New hope for the visually impaired

It has long been thought that people who were blind from birth would lack the ability to process visual information, even if their sight were restored. A recent study at Hebrew University’s Safra Center for Brain Science suggests otherwise.

The authors of the study developed “a visual-to-auditory sensory-substitution algorithm,” a method to transmute visual information into audio information to create what the researchers called “soundscapes.” Participants in the study would listen to these soundscapes and report what they “saw.” As reported in the journal Neuron, the participants were initially able to identify simple objects and shapes, but with additional training could actually identify letters and facial expressions.  In videos released with the article, the subjects describe what they are “seeing.”

Even more remarkable than what the participants reported is what was happening in their brains. The researchers observed that when the visually impaired participants–individuals who had never processed any visual information–were “seeing,” their visual cortex was engaged in the same ways that a sighted person’s cortex would be. The part of the brain that usually processes letterforms is called the visual word form area, or VWFA. Conventional wisdom indicated that this area would remain dormant in a congenitally blind person, since the person would never have developed that capability. MRI scans revealed activity in the VWFA, regardless of the type of sensory input involved.

This is exciting for two reasons. First, the technology used to create these soundscapes may literally open new worlds of possibility for blind and visually impaired individuals.  As the algorithms are refined, and with more training, there is reason to believe that people using this technology may be able to receive and process very complex amounts of information that would otherwise be inaccessible to them. Second, as new treatments and technology allow more people to recover their sight, their brains (specifically the visual cortex) may be able to learn to process visual information after decades of inactivity.

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