How can you tell if your baby hears you? Your beautiful newborn looks at you, tracks your eyes and seems to follow your every word. Your baby may grasp your hair as you speak to him or her softly, yet it’s still difficult to tell if you are really being heard.
Experts know that there are risk factors that can help identify small children with hearing loss, but before routine screening after birth became standardized, many children with hearing loss went undetected — a missed opportunity to help families seek treatment.
That all changed on June 2, 2000, when hearing researchers and advocates working with lawmakers celebrated the passage of the universal newborn hearing screening law in Florida. Before that date, we knew how to help children who had relatives with hearing loss, children who may have suffered from viral infections during pregnancy or from meningitis, or who had physical findings associated with hearing loss. What we learned from universal screening, however, is that only half of the infants with hearing loss had any risk factors. The other half were difficult to identify without testing.
The call for universal newborn hearing screening began in the 1960s with the observation that children who didn’t hear well were not discovered until 2 1/2 to 3 years of age. By that time, children are already delayed in their speech and language development, setting them back socially and scholastically. Children with hearing impairment who are found early do much better at developing speech and language skills.
Previously, we did not have the technology to screen every newborn. But now we can begin testing for hearing in the first days or hours of life. Our tools for checking a baby’s hearing are objective tests that do not harm the child in any way.
The otoacoustic emissions test is performed by placing a small sound tube into the child’s ear canal and letting the computer present distinct sounds to the ear. After each presentation, the computer waits a few thousandths of a second to record the return sound generated by sensory cell movement in the inner ear. The test is effective because these sensory cells are very sensitive and the first to be damaged if a disease or medication harmed a baby’s hearing.
In the auditory brainstem response test, small electrodes are placed on the baby’s head while the ear hears clicking sounds. When the ear hears a click, organized neural activity along the hearing nerve goes up through the brainstem and can be recorded. If we see evidence of that neural activity, we know that the ear had to be working to generate that follow-on activity.
We know from brain development studies that there is a critical period for both brain development and establishing a foundation of language. That is why hearing screening is now done in the newborn period. A newborn’s hearing screen may be passed immediately or not. If the hearing screen in the hospital is not passed, it does not indicate a certain hearing loss. It does mean that further testing should be done.
If there is a problem with hearing and we miss that window of opportunity, therapy can help, but cannot make up for time lost. The research shows that if we can find hearing loss early and have all of the required interventions (e.g., hearing aids, language stimulation therapy, etc.) in place by 6 months of age, a child has a good probability of developing age-appropriate language skills. And language is highly correlated with decision-making and basic intelligence.
If significant and permanent hearing loss is detected, what can be done? A great deal! We start with hearing aids to amplify the sounds of speech and nature, making them easier to hear. We also begin intervention to teach the child how to hear and maximize use of residual hearing for speech understanding. If hearing aid technology is not appropriate or sufficient for the child, we refer the patient to the UHealth Ear Institute’s Cochlear Implant Program for evaluation of implant candidacy.
Instead of amplifying sound, a cochlear implant stimulates the hearing nerve with small pulses of electrical current trying to imitate how the normal ear would activate the hearing nerve. The technology has improved through the years so that most children are capable of carrying on a normal, typical conversation with good language and excellent voice quality.
There is much we can do to alleviate the effects of hearing loss on speech and language in children. The key is early detection and early intervention.
Robert Fifer, Ph.D., associate professor and Director of Audiology and Speech-Language Pathology at UHealth – University of Miami Health System, specializes in pediatric audiology and early identification of hearing loss in newborns. UHealth is nationally and internationally acclaimed for education, research, patient care and biomedical innovation. For more information, visit UHealthSystem.com/patients/pediatrics.