T failed his newborn hearing screen at the hospital shortly after he was born (for both ears). At the time, we weren’t too concerned, since it’s fairly common for babies to fail the hearing screen due to fluid or other factors from the delivery. So, we scheduled a follow-up screening test for a few weeks later.
Both the newborn hearing screen and the follow-up screening test measured Otoacoustic Emissions (OAEs). In this test, a sound is played into the ear through a probe inserted in the ear canal, and emissions generated by the inner ear are recorded by a microphone also inserted in the ear canal. OAEs disappear (that is, the inner ear generates no emissions) when the inner ear is damaged, and so they are useful as a screening tool for hearing loss in infants. If OAEs are recorded, this generally indicates no more than a mild hearing loss.
T failed the follow-up screening test as well, and this time I was more worried. Our audiologist suggested doing an Auditory Brainstem Response (ABR) test as the next step to more definitively determine whether or not T had a hearing loss.
In the ABR test, probes are inserted into the ear canal (like in the OAE screening test), and sounds of different frequencies (pitches) and amplitudes (loudness) are played into the ear. Electrodes are placed on the scalp and record changes in brain activity in response to the sound. The audiologist then looks for the sound amplitude at which they can first detect a change in the brain activity response. This sound amplitude at which a change is first detected is related to hearing threshold at that particular frequency, so for people that can’t participate in testing for an audiogram (infants!), the ABR can estimate hearing loss at different frequencies.
The ABR test showed that T had a mild-moderate bilateral hearing loss. A follow-up ABR a few weeks later showed that the hearing loss was more on the mild side. The two ABRs were completed by the time T was 2 months old, and T began wearing hearing aids at 3 months old.
Through our state’s Early Intervention program, T receives twice a week speech therapy services, which he began at 4 months old. A lot of people are surprised that speech therapy exists for such young children, and ask me what speech therapy involves! Many of the posts here will document his speech therapy sessions, but in short, the speech therapy is more “communication therapy” – the primary goals for him as an infant are to learn to produce different vowel and consonant sounds, to encourage him to produce vocalizations, and to understand the turn-taking nature of conversation (I say something, you say something back, etc.). Additionally, since children with hearing loss are at a higher risk of developing language delays later on, receiving speech therapy from such an early age ensures that his language development is on track now, rather than finding out about a delay later on.