May 2018 Science News
Researchers are working to synchronise cochlear implant signals to provide a more realistic hearing experience for deaf adults and children. Using both ears to hear increases speech recognition and improves sound localisation. In essence, it helps you to identify a friend's voice so you can follow her amusing anecdote over the din of a cocktail party. Ruth Litovsky, a researcher at the University of Wisconsin-Madison, wants to bring this advantage to people who use cochlear implants. "Twenty years ago, [the medical community] decided to give [deaf] people two implants, one in each ear, to see if it would improve their ability to hear better in noisy environments, so that children could integrate into classrooms and adults into the workplace more easily," Litovsky said. "I believe bilateral implantation has had a significant, positive impact on their quality of life, but they still struggle with noisy environments."
Litovsky says a new technique that synchronises the cochlear signals that stimulate the brain in a way that is similar to people who can hear normally. "The first time I present a [deaf] child or adult with sounds that are truly coordinated, their face lights up as they experience that aha! moment where they truly hear stereo sound," Litovsky said. "The goal is to make this method work outside the lab, but it remains a challenge from an engineering point of view.” According to Litovsky, the brain acts like a little computer. It uses synchronised information to calculate the difference as sound waves arrive at each ear from different locations. These mental calculations help people locate sounds and separate speech from noise. Currently, individual cochlear implants send information to the brain independently, but the brain does not integrate the signals in an optimal way. Litovsky is committed to synchronising auditory experiences especially for young children. The brain loses plasticity during development, so it is harder to learn to synchronise sounds later in life.
Now, the engineering setup for the technique is limited to the laboratory, but she hopes that researchers can eventually partner with implant manufacturers to make synchronous hearing a reality.