A recent study carried out by researchers from the National University of Quilmes (UNQ) and the National University of Tres de Febrero (UNTREF) showed that in the absence of vision, auditory space can be calibrated by tactile and proprioceptive information, which is the brain’s ability to know the exact position of all parts of the body. The results, which were recently published in the prestigious Journal of Experimental Psychology: Human Perception and Performance (American Psychological Association – APA), showed that blind people were more accurate than sighted people perceive the distance of the speakers located in the peripersonal space, that is, within reach of the listener’s hand.

How did they verify this?

The researchers conducted a series of auditory distance experiments on a group of blind people and on a group of sighted individuals wearing blindfolds. This is how he explains in dialogue with this UNQ science news agency Ramiro VergaraConicet researcher and work reference: “We measured the perceived distance of sound sources located within and outside the listener’s reach, distances between 20 cm and 280 cm, to report the perceived distance from the sound source through two response methods: reports verbal and the reaching technique, which consists of the participant, after hearing the stimulus, the action of trying to grab the speaker”.

Considering that the blind were more accurate than the sighted in the perception of the distance of the speakers located in the peripersonal space; when placing the speakers out of range, however, blind participants performed worse. “Out of range, blind people don’t have accurate spatial information to measure auditory information from distance.” Vergara explains that “vision is the sense that provides the most reliable information about the environment that surrounds us and the objects located in it. This causes vision to be used by the brain to calibrate spatial information from the other senses.” He continues: “Vision is known to be crucial for calibrating information related to auditory perception of the environment. This is why people with total blindness have deficits in various auditory localization tasks.”.

investigation and action

This auditory distance can be calibrated with non-visual information, opens the door to the design of various training and rehabilitation strategies that improve the perception of distance in blind people. In this sense, Vergara believes that it would be interesting “to study whether the performance of the blind in the far field can be improved through training tasks that involve some type of multimodal feedback”.

To account for this work, carried out under the project Auditory and Visual Perception of Distance directed by Vergara at the Laboratory of Acoustics and Sound Perception at UNQa specific agreement was negotiated with the Theater of the Blind of the Autonomous City of Buenos Aires and a link (through the health and disability division of the UNQ) with the Argentine Federation of Institutions for the Blind and Visually Impaired (FAICA).

According to data provided by the World Health Organization, it is estimated that worldwide, 217 million people have moderate to severe visual loss and 36 million are totally blind. “These numbers reflect the importance of further studying the way in which different auditory capacities, including the calibration of the sound space, are affected by vision loss”, concludes the project director.

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