Early childhood deafness causes changes in how the brain processes sound. In childhood, the structure and the function of the auditory system, which processes sounds in the brain, develops as a response to sounds. In a deaf child, a functional reorganization of the auditory system occurs, and the child responds more to visual stimuli. Now, information regarding how mild-to-moderate hearing loss impacts brain processing during childhood is coming to light. A recent study is examining how mild-to-moderate hearing loss in children changes how the brain processes sound.
Sound funnels into the ear canal, causing the eardrum to vibrate from the noise. These sound vibrations then move into the cochlea. In the cochlea, auditory nerve fibers transmit signals to the brain. Once inside the brain, relay stations consisting of neurons receive the signals and decode them, causing a sensation. The brain then interprets the signals as sounds.
The current screening process for newborn babies does an acceptable job of detecting moderate-to-profound levels of hearing loss. Unfortunately, this process does a poor job of finding mild hearing loss. The result is that children may have a mild hearing impairment that goes undetected until later in childhood. Since children with hearing loss tend to lag behind their peers in terms of language development and academic performance, the detection of mild hearing loss can lead to early intervention and an improved outlook for these children.
An electroencephalogram (EEG) technique measures the brain responses of 46 children diagnosed with permanent mild to mild-to-moderate hearing loss while the children are listening to sounds. The researchers are aware that children’s brains develop through exposure to sounds, so they are not surprised that even mild-to-moderate levels of hearing loss can cause changes in the brain. The task is identifying these problems early.
The results of the study demonstrate that younger children with hearing loss show typical brain responses. Their brain responses are much like that of children with normal hearing. The brain responses of older children, however, are smaller than those of their normal-hearing peers.
Six years later, the researchers are re-testing a subset of a group of younger children from the original study. In this study, the researchers are confirming that brain responses change as the children age. The responses given by the children when they were younger have disappeared or grown smaller. No evidence is present to suggest the children’s hearing loss is worse, suggesting a functional reorganization is occurring.
Hearing loss affects children’s ability to develop speech, language, and social skills. The earlier these children receive a hearing loss diagnosis and treatment, the better their chances are of reaching their full potential in speech, language, and social development. If you suspect that your child might have a hearing loss, schedule a hearing evaluation with a hearing healthcare professional today. Please remember that the key to success is early diagnosis and treatment.