Deafness in early childhood is known to cause lasting effects on how the brain processes sounds, but new research indicates that even mild to moderate hearing loss can lead to the same kind of effects.
The auditory system develops as a child grows and is exposed to a variety of sounds. What a child hears (or doesn't hear) directly affects the structure and function of this system. If a child is deaf or suffers from a severe hearing impairment, the auditory system actually reorganizes itself so that the brain can up its focus in other areas, such as visual input. That is why a deaf person might have more acute vision than the average person; the brain makes up for the loss elsewhere.
Scientists have been aware of this phenomenon for some time now, but the newest research indicates that similar changes occur even when hearing is only mildly impacted.
Dr. Lorna Halliday, of the MRC Cognition and Brain Sciences Unit at the University of Cambridge and her research team discovered that even mild hearing loss had a lasting impact on the structure and function of children's brains.
The team measured the brain responses of 46 children who had been diagnosed with permanent mild-to-moderate hearing loss while they were listening to sounds. They found that while the children were still young, their responses were similar to those of children with normal hearing. But as they aged, their responses slowed, looking more like those of children with severely impacted hearing. Apparently, brain development was affected over time, even when hearing loss was minimal.
According to the researchers, their findings may have implications for how babies are screened for hearing loss, and what follow up care is required for those with mild-to-moderate hearing loss.
The brain is amazingly adaptive, changing and growing depending on its specific needs. But all of its systems will do best when they are in balance. Treating even mild hearing loss is best.