Despite some theories that visual cues may hamper auditory processing, researchers say a new study shows lipreading may have a beneficial effect on a person’s brain and their ability to hear with a cochlear implant.
Researchers at the National Institute for Health Research Nottingham Biomedical Research Centre conducted a first-of-its-kind study to measure cochlear implant users’ brain activities while lipreading. The study examined the changes in brain responses before and after implementation.
The study found that, “In contrast to existing theory, the more a person’s brain became responsive to lipreading the more it also became responsive to sounds delivered through their cochlear implant, and the better they were able to hear.”
“…the more a person’s brain became responsive to lipreading the more it also became responsive to sounds…”
The team used a brain imaging method called FNIRS (functional near-infrared spectroscopy) to measure brain activity of the lipreaders. The technique measures how much oxygen different parts of the brain are using. (The more active parts of the brain use more oxygen.)
“We measured how hearing parts of the brain responded to visual speech before the volunteers received their cochlear implant, and then again 6 months after the implant had been switched on,” lead researcher Dr. Carly Anderson said in the report. “From this, we could see how their brain activity changed over that time.
“We also tested how well they could hear speech with their implant 6 months after switch-on, using speech tests which require volunteers to repeat back spoken sentences played to them.”
The study shows that activation of hearing parts of the brain by lipreading does not limit the ability of these brain regions to be activated by speech sounds heard through the implant. It also doesn’t limit the ability to hear with a cochlear implant.
In fact, it shows the opposite: increased activation by lipreading could help achieve greater restoration of hearing following cochlear implantation. Visual cues may help people with cochlear implants, rather than hinder them.
“Visual cues may help people with cochlear implants, rather than hinder them.”
The researchers stress that they cannot say what exactly is linking brain activity to sound and lip-reading together. They have not compared peoples’ ability to lipread in this study. The team did not train people to become better at lipreading from before to after cochlear implantation or examine whether this helps a person to hear well with their implant.
These are possible avenues of research in the future.
Do you wear a cochlear implant? How much do you rely on lipreading?