Hearing and Brain Development

Hearing is crucial for brain growth and learning, which is why it’s important you know how your baby is hearing. Sound travels through the ears to your baby’s brain, becoming a key factor of their learning. This auditory information helps develop connections in the brain that allows your baby to begin to listen and talk. The first 3 years of life are the most important time for a child to learn language, spoken or signed. 

Your Baby’s Test Results

When will my baby’s hearing be screened? 

Your baby’s hearing will be screened before they leave the hospital or birthing center, using a pass-fail test. If your baby did not have a hearing screening completed, contact the House Children’s Hearing Center immediately to ensure that your baby is tested during the first month of life. 

What happens if my baby fails the hearing screening? 

If your baby fails the newborn hearing screening, a thorough evaluation will be needed to confirm their hearing status. This comprehensive evaluation is made up of different tests that will measure how well your baby can hear, from the moment the sound enters the ear and travels to the brain. One of the tests is an Auditory Brainstem Response (ABR) test, which will measure how the auditory nerve and brainstem respond to sound. During this test, your baby wears small earphones and has electrodes painlessly placed on his or her head. The electrodes adhere and come off like stickers and should not cause discomfort. Your baby sleeps during this test.

Understanding your baby’s test results

What do the test results mean? 

If your baby is diagnosed with hearing loss, a pediatric audiologist from House Children’s Hearing Center will discuss with you the results and what the next steps will be to help your baby reach their full potential. 

The discussion of the results will include: 


An audiogram is a visual representation of your child’s hearing levels. Understanding your child’s audiogram will help you better understand their hearing loss.  

Range of Hearing Loss 

You will learn the degree of your child’s hearing loss. Hearing loss can range from mild, moderate, severe, to profound hearing loss. The hearing loss can be in one ear only (unilateral) or in both ears (bilateral). 

Type of Hearing Loss 

There are 3 main types of hearing loss: 

  1. Conductive hearing loss (CHL)– The problem is in the outer and/or middle ear, which does not allow sound to be properly reach the inner ear. Such problems can include excessive earwax, an ear infection, or a problem with how the ear is formed. This type of hearing loss may be corrected with medical treatment or through surgery.  
  2. Sensorineural hearing loss (SNHL)– The problem is in the inner ear (the cochlea), which is the part of the ear that receives and transfers sound through the nerves to the brain. This type of hearing loss is permanent and cannot be corrected with surgery. Hearing devices, such as hearing aids or cochlear implants, can help your baby learn to listen and speak.  
  3. Mixed hearing loss (MHL)– The problem is in the outer or middle ear AND in the inner ear, a combination of conductive and sensorineural hearing loss. Even if the outer or middle ear problem is corrected, there will remain permanent hearing loss due to inner ear damage.  

A less common hearing problem can occur when there is a problem in the hearing nerve or in the connection between the hearing nerve and the cochlea. This is known as Auditory Neuropathy Spectrum Disorder (ANSD). This means that the brain receives a jumbled signal that may cause difficulty understanding speech clearly, especially in the presence of background noise. Children with ANSD may have normal hearing or varying degrees of hearing loss that can fluctuate over time. 

Cause of Hearing Loss 

The cause of your baby’s hearing loss may be determined through additional testing, but in many cases, it may be unknown. Hearing loss can be caused by several different factors, including genetic or environmental factors. 

Genetic factors are passed down from one or both parents and hearing loss may exist along with other conditions as part of a syndrome.  

Environmental factors can include an infection contracted during pregnancy, lack of oxygen at birth, or issues related to low birth weight and prematurity.  

Hearing loss can also be caused by lifesaving medications given to infants in the NICU or from acquired infections, such as meningitis.

Other Evaluations Needed

Your baby will be referred to see a pediatric ear, nose, and throat (ENT) doctor for a medical evaluation, following the diagnosis of hearing loss. The ENT doctor may order additional testing, such as a CT scan or MRI scan, to further determine the cause of the hearing loss. If hearing aids are recommended, the ENT doctor will also provide a prescription for your baby to use hearing aids.

Doctor with mother and child
Young girl watching ipad with cochlear implants