Summary: Researchers introduced a multisensory solution that significantly improves auditory spatial perception in hearing aid users and cochlear implant recipients, using tactile feedback to enhance sound localization abilities.

Key Takeaways:

  1. Auditory Spatial Deficit Identified: Researchers discovered that individuals born with hearing challenges, even with hearing aids or cochlear implants, have difficulty localizing sounds, particularly moving sources.
  2. Tactile Feedback Solution: The team developed the Touch Motion Algorithm (TMA), which uses fingertip tactile feedback to represent sound spatial positions, allowing users to quickly sense spatial cues.
  3. Multisensory Integration: Combining auditory and tactile inputs resulted in improved sound localization accuracy, highlighting the potential for tactile cues to enhance auditory rehabilitation technologies.

A team of researchers has identified a significant deficit in auditory spatial perception among hearing aid users and cochlear implant recipients and introduced an innovative multisensory solution that leads to notable improvements in this ability.

The research, which was developed by researchers from the Ivcher Institute for Brain, Cognition, and Technology (BCT Institute) at Reichman University (Herzliya, Israel), was recently published in the prestigious journal iScience, and highlights the challenges faced by individuals born with hearing challenges, even after years of hearing aid use or cochlear implantation.

“We intentionally chose people born with congenital auditory deprivation because these individuals offer a unique opportunity to explore how sensory representations are formed,” says Adi Snir, PhD, first author of the paper and postdoctoral fellow at the BCT Institute. “What we found were severely impaired auditory spatial capabilities, with significant difficulty in localizing sounds, especially when tracking moving sound sources, even among individuals with bilateral cochlear implants.”

The auditory system constantly compares the arrival times and levels of sounds, quickly calculating differences to locate the positions of sound sources. 

“With hearing impairment, there is a change in the frequency ranges and resolution of perceived hearing, often compounded by additional distortions caused by hearing devices, which interfere with this process, particularly for moving sounds,” says Katarzyna Cieśla-Seifer, MSc, PhD, co-author of the paper and postdoctoral fellow at the BCT Institute and the Institute of Physiology and Pathology of Hearing in Warsaw.

New Tactile Feedback Solution

Inspired by the function of the auditory system, the researchers developed a technology (Touch Motion Algorithm – TMA), which delivers tactile feedback through the fingertips, performing intensity adjustments to represent external spatial positions and movement. 

“We wanted to test whether we could represent spatial information in a way that reflects the auditory system’s processes, but using an alternative sensory modality—in this case, touch,” Snir says.

The participants quickly developed the ability to sense spatial cues through tactile feedback and achieved near-normal accuracy in localization tasks. The team also explored the effect of combining auditory and tactile inputs, with participants reporting that the combination significantly simplified the localization task.

“The feedback we received from participants emphasizes the value of integrating tactile cues to improve the experience for people with hearing impairments,” says Cieśla-Seifer. “It also underscores the importance of multisensory integration in auditory rehabilitation.”

Significance for Understanding Spatial Representations

“These findings are particularly exciting because they have implications for understanding how spatial representations develop in the brain,” says Amedi, senior author of the study. “Hearing is the only modality capable of naturally representing our entire 3D environment, so lacking access to this information from birth might cause some deficits in spatial abilities for this population.” 

However, the researchers found that participants were able to rapidly perform spatial tasks using tactile cues, underscoring the remarkable learning capacity of the adult human brain and supporting the idea that spatial representation is not necessarily tied to any specific sensory modality.

The study’s findings carry profound implications for the future of sensory rehabilitation. “By harnessing tactile feedback, the potential to enhance existing assistive technologies could significantly improve the quality of life for millions of people worldwide,” says Amedi, who is also founding director of the BCT Institute

Featured image: Adi Snir, Katarzyna Cieśla, Rotem Vekslar, Amir Amedi. Photo: Reichman University