The first question I ask a family when I see them – either the first time or when they come in for re-evaluation is “What does your baby or child hear with technology?” If babies are doing well with hearing aids, I expect the parents and the therapist working with the family to be able to tell me what sounds a child is responding to and what the child cannot hear. If a family cannot tell me what a baby is hearing, something is wrong.
A few weeks ago I was doing some clinical training in another state and the auditory verbal therapist asked if I could see a baby for evaluation. The baby had failed newborn hearing screening and had been evaluated at another center. The baby was tested using ABR, and a moderately severe hearing loss was identified. The baby was fit with hearing aids which she had been wearing for about 4 weeks. The audiology center had recommended that the baby return every 6 weeks for repeat ABR to monitor hearing? Who was going to monitor performance with hearing aids?
Why is it important for parents to know what their baby hears?
When the parents came in I asked them what the baby heard with hearing aids. They looked at each other and shook their heads. They could not tell me what the baby heard, what sounds the baby alerted to, etc. This is not a good thing for a number of reasons. If parents do not know what their baby hears with hearing aids how can we expect them to be motivated to keep the hearing aids on? And if a baby is not keeping hearing aids on, how can we expect a baby to learn to listen? If parents do not see responses they cannot be optimistic about their babies ability to learn to listen and talk. On the other hands if the parents see responses to sound, they have reason to be optimistic that the baby can learn to listen and talk.
ABR testing is a critical part of the diagnostic protocol and, although ABR test results are closely related to hearing, ABR is in fact not a measure of hearing. In addition, while ABR test results are useful in identifying hearing loss, it is not useful for measuring performance with technology. So how do we know if the hearing aids are doing what we need them to do?
Will real-ear testing tell us what the baby hears with technology?
Real ear testing is an important way to start when fitting hearing aids but we need to verify what a child is hearing with technology and real-ear will not tell us what the child hears. With parents telling me that they could not tell if the baby heard anything, I became concerned. We really needed to know what the baby heard.
Behavioral testing is the gold standard. It is the only way we can measure the entire auditory system and know what the child is responding to. For older children, we routinely test using behavioral testing – visual reinforcement or conditioned play. Infants are a little more difficult to test but it is absoultely possible. I tested the baby using behavioral observation audiometry using changes in sucking to identify responses. Testing indicated hearing with technology at around 45 dBHL. Not surprising that the parents did not know what the baby was hearing. She wasn’t hearing at sufficiently soft levels to hear normal conversation and was not even aware of soft conversation or speech from a distance. I adjusted the hearing aids and she returned the next morning for re-evaluation. (More information about behavioral observation testing in infants can be found in Madell and Flexer (2014) Pediatric Audiology: Diagnosis, Technology and Management, Thieme, NY. Madell & Flexer)
Hearing with change in hearing aid settings?
The next morning I again asked the parents what baby Rose heard with her hearing aids. This time the answer was very different. They were very excited about what baby Rose could hear. They said they were very impressed. She was alerting to sound, turning to look for sound, and babbling a lot more with hearing aids on. I retested her hearing with the hearing aids and thresholds were obtained at 20-25 dB throughout the frequency range. The parents were elated. They could not believe the difference in what their daughter could hear and had a much more optimistic feeling about what was possible.
It is essential to verify hearing with technology
We cannot assume that real-ear is accurately telling us what a baby (or anyone else) is hearing with technology. Real-ear tells us what reaches the tympanic membrane but not what is reaching the brain. Real -ear is a starting place, but without verification we will not know what the child is hearing. Unless we can assure that a child is hearing with her technology we cannot expect children to learn using audition. Even if speech perception testing is a possibility, aided thresholds really provide us with critical information about what a child is hearing. Only by fine tuning the aided thresholds can we assure that the child is hearing throughout the frequency range and hearing sufficiently to hear all the phonemes.
Parents as monitors
Parents are the most critical monitors of a baby’s listening. They should be encouraged to monitor aided hearing daily. I suggest that parents present one of the Ling sounds every morning, and record if the baby can hear and alert to the sound. Parents can then report to the audiologist what sounds a baby hears and what sounds the baby does not hear. The audiologist can then use the information about the child’s responses to sound to adjust the technology assuring that the baby can use audition to learn.