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When Do Babies Start Hearing After Birth?

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Babies are born with a certain level of hearing ability, and the sense of hearing improves as the baby grows. Babies achieve age-related hearing milestones, and the lack of these achievements might indicate problems with hearing. But how can parents know about it?

In this MomJunction post, we tell you about a baby’s normal hearing ability, development of hearing, hearing screening tests, and probable causes of deficiency.

When Do Babies Start Hearing After Birth?

According to the American Speech-Language-Hearing Association (ASHA), babies begin to react to sounds at the age of three months (1). It is believed that the baby, as a fetus, begins to recognize and react to sounds from as early as the sixth or seventh gestational month (2).

But proper development of hearing happens in the babies only after they are born.

Newborn Baby Hearing Development

According to the U.S. National Institute on Deafness and Other Communication Disorders (NIDCD), a baby with a healthy hearing sense will achieve the following developmental milestones (3).

From birth to three months

  • Startles at loud sounds
  • Calms down or smiles on listening to your voice
  • Starts or stops sucking while feeding in response to sound
  • Makes a different sound for each specific need

From four to six months

  • Moves the eyes in the direction of a sound
  • Observes the toys that make sound
  • Responds to alteration in the tone of your voice
  • Begins to pay attention to music

Seven months to one year

  • Turns the head and looks in the direction of the sound
  • Begins to respond when called by their name
  • Identifies words for common things and people like a cup, truck, juice, or daddy
  • Starts to respond to simple words like “no,” “come here,” “want more,” etc.
  • Listens to songs and stories, but for a short time

Each baby is different, and if a baby misses a milestone by a few weeks, it does not necessarily indicate a problem.

How To Know If Your Baby Is Hearing Clearly?

There are various tests done after a baby’s birth to check their hearing abilities. However, the baby’s hearing abilities can only be gauged as they grow older. If the pediatrician suspects a problem in the baby’s hearing abilities, then they may recommend advanced tests at a later date or a later age.

Note that babies do not react to sounds like that of a telephone or doorbell ringing when they are in a deep sleep because they have a more sound sleep than adults.

When To Worry About Your Newborn’s Hearing?

Babies, when awake, startle to sudden loud bangs or sounds. The following are a few signs that may indicate a hearing problem (4).

  • Not being startled by loud sounds
  • Not reacting and turning to a sound even after six months of age
  • Looking at you only when they see you and not when they hear you
  • Seems to be alerted by some sounds but not by others

These issues do not always confirm a hearing problem. Babies might show a temporary diminished hearing during ear infections or an episode of cold and cough. They may also show no reaction when they are engrossed playing with an adult or a sibling. Therefore, do not panic but consult a doctor before arriving at a conclusion.

How To Help A Baby Develop Their Hearing Abilities?

Hearing abilities develop naturally and reach the requisite milestones at a specific age. One can stimulate healthy development through various means.

  • Babies tend to recognize and respond to the song or rhyme that they repeatedly hear in the mother’s womb, after birth, too (5). Sing the same rhymes for your baby once the baby is born to help them connect with the song.
  • Start reading bedtime stories to them after they grow up a bit. They might not understand, but it will help them build a connection with the words and form a reading habit.
  • Play music and clap along with the song. It will encourage the baby to do the same.
  • Get toys that have music in them.
  • Encourage them to play with rattles.

Factors That May Affect Your Infant’s Hearing

There are various factors that might affect a newborn’s hearing. Here are some of the common reasons (4) (6).

  1. Hearing issues can be due to genetic predisposition.
  1. A mother affected by certain viral infections during pregnancy might have babies with hearing problems. Such viral infections include:
  • Cytomegalovirus infection
  • Herpes
  • Measles
  • Rubella
  • Syphilis
  • Toxoplasmosis
  1. Premature birth and low birth weight can also cause hearing defects.
  1. Birth defects may cause structural changes in the ears and other internal organs, thus leading to hearing loss.
  1. Ear infections after birth usually cause temporary hearing loss. Although rare, some severe ear infections might cause damage to nerves or bones of the internal parts of the ear.
  1. Some other conditions that might cause hearing loss are (7):
  • Head injuries
  • Low Apgar score (score for newborn tests)
  • Jaundice
  • Bacterial or viral meningitis
  • Prolonged mechanical ventilation
  • Antibiotics such as gentamicin, tobramycin, kanamycin, and streptomycin
  • Earwax or fluid behind the eardrum
  • Objects such as toy, crayons, or food stuck in ear canals
  • Being surrounded by machines that make loud sounds

Hearing loss in babies can display the following characteristics.

  • It can be unilateral, bilateral, or both.
  • Be mild, moderate, severe, or profound in intensity.
  • Profound hearing loss is commonly called deafness.
  • In some babies, the inability to hear worsens with time.

Screening For Your Baby’s Hearing

The US Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatrics recommend that all babies get screened for hearing loss before they’re one month old (4).

Screening for newborn’s hearing ability is done at every hospital mostly before discharge after birth. According to the CDC, over 98% of newborns in the U.S. receive a newborn hearing screening (8).

One of the following three screening methods may be deployed by your baby’s pediatrician (9):

  1. Automated auditory brainstem response (AABR) This test evaluates the part of the nerve that carries sound waves to the brain and the brain’s response to those sound waves. In this test, miniature headphones are put into a baby’s ears, and electrodes are attached to the baby’s head. Music is played into the baby’s ears, and the response elicited by the brain is recorded. your baby might have a hearing problem.
  1. Otoacoustic emissions (OAE) test A microphone and headphone are attached to a baby’s ear. When the sound is played, the waves echo back through the microphone. If the microphone cannot record any echo, your baby might have hearing loss.
  1. Brain audiometry evaluation This test evaluates a baby’s response to sound. It evaluates all the parts of a baby’s hearing. A headphone is used to transmit sound to the baby’s ear, and a change in the baby’s behavior is noticed. Babies with full hearing power respond by sucking on a pacifier, being quiet, or by searching for the source of the sound.

If a baby fails to pass the initial test, it does not necessarily mean that the baby has hearing loss. Up to 10 percent of babies in the U.S. fail in their first hearing screen, but very few babies out of them actually have hearing disabilities (9).

Fluid in the baby’s ear, too much background sound, or severe crying can cause the false-negative results of the primary screening test.

Frequently Asked Questions

1. Are a baby’s ears more sensitive than adults’?

Yes, babies are much more sensitive to sounds than adults. Their brains are not conditioned to distinguish one sound from the other, and also they cannot identify the source of different sounds (10).

2. What is too loud for the baby’s ears?

The pain threshold of a human ear is 120 decibels, and any consistent noise of more than 85 decibels can cause hearing loss. Babies are more sensitive to sounds and hence cannot tolerate very loud sounds like that from factories, trains, planes, chain saw, pistols, etc. The Sight and Hearing Association (SHA) suggests that parents test toys before buying them for their children. If a toy is too loud for you, then it is certainly not suitable for the baby to play (11).

Newborns can hear as soon as they are born, but the hearing ability gets better as they grow. Take the necessary precautions to avoid permanent hearing loss in babies due to loud sounds. Hearing issues in babies might occur due to a variety of reasons. Although not very common, it does affect babies. Prompt consultation with a pediatrician can help initiate a cure for the underlying cause or efficient management of the condition.

Do you have any experiences to share about hearing development in your baby? Let us know in the comment section below.

References:

1. Birth to One Year; American Speech-Language-Hearing Association
2. Farzaneh Zamiri Abdollahi et al., Auditory Development in Infants; Global Journal of Otolaryngology
3. Your Baby’s Hearing and Communicative Development Checklist; National Institute on Deafness and Other Communication Disorders
4. HEARING LOSS AND YOUR BABY; MARCH OF DIMES
5. Eino Partanen et al., Prenatal Music Exposure Induces Long-Term Neural Effects; PLOS ONE
6. Hearing loss – infants; U.S. National Library of Medicine
7. Non-Genetic Hearing Loss; Baby hearing organization
8. Newborn Hearing Screening FAQs; American Academy of Pediatrics
9. Hearing loss; Baby’s first test
10. Babies Have A Different Way Of Hearing The World By Listening To All Frequencies Simultaneously; University of Washington
11. Dez Duran-Lamanilao, Noise Levels for Babies – When Sounds Become Too Loud; Gulf Coast Audiology

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