Fetal Development – Know Everything About Your Baby’s Hearing Development

• The process of the auditory system in an embryo starts first in the 5th week of gestation. By this time the outer layer of the embryo forms the inner ear.
• At the 9th and 10th week, the outer ear starts showing up externally.
• By the 18th week, the position of the ear shifts to its exact position and starts doing its job.
• At around 20 weeks of pregnancy when your baby can become sensitive to sound and even react to it.
• It takes around 25 to 28 weeks for the hearing system to develop completely. Your baby can react to different types of sounds after that.
• You can even notice facial expression changes due to different sounds during the third-trimester ultrasound. You can also feel your baby startle at sudden loud sounds.

Early Fetal Development of Baby’s Ears

The development of the ear and its function is a slow process. It starts at early pregnancy (around the 5th week) and goes till mid-pregnancy (25 weeks).

The ear consists of three parts, the inner ear, middle ear, and outer ear. The development of each part starts at different stages of pregnancy.

1. Development of the Inner Ear

During the fifth week of gestation two tiny spots appear at the two ends of the head of the embryo. These later form the inner ear. They then fold inward to form ear sacs beneath the skin. These sacs enlarge to become tubes and the cochlea, the main hearing organ forms at the end of this tube.

2. Middle Ear Development

The middle ear is a tube-like cavity that consists of 3 ear bones that vibrate in reaction to outward sounds. During the eighth week of gestation, these tiny bones start forming. At first, they appear as small clumps of tissues and then slowly they harden as a bone.

3. Signal Between The Brain And The Ear

The tiny hairs that work as sound transmitters develop in the cochlea at around 12 weeks. These hairs then connect the sound waves with the nerves connected to the brain. This connection is completed in 16 weeks. After that, your baby can hear faint sounds.

4. Complete Formation of the Ear

For the complete formation of the ear, it will take many more weeks. It can take up to 30 to 35 weeks to fully develop the outer ear canal, middle ear cavity, and external part of the ear.

What Sounds do Babies Hear in the Womb?

Your baby can hear faint muffled sounds from within your womb. It is similar to the sounds that you hear when diving underwater. This is because the sound passes through a lot of layers like your skin, your uterus wall, and then through the amniotic fluid to reach up to your baby’s ears. Also, all the other sounds that your body constantly produces, like breathing, digestion, heartbeat, make it more complex and confusing for your little one.

But your baby can clearly perceive your voice more than any others. This is because your sound reverberates through your body when you speak. Your baby can also become alert and even respond to your partner’s voice.

So you can read aloud your favourite book or listen to your favourite music and your baby will also show a likeness towards them.

[Read : Does Reading Books During Pregnancy Make The Child Smart?]

Factors That Hamper Your Baby’s Hearing Development During Pregnancy

During pregnancy, you need to be careful of certain stuff that can hamper your baby’s hearing process. The precautions you must take to ensure proper hearing development of the foetus include

1. Avoid Loud Sounds

Prolonged loud music can damage your baby’s hearing ability. So you should avoid exposure to routine noise of more than 115 decibels. You must keep a distance from loudspeakers or home theatres.

You should avoid going to rock concerts or shooting practices. Wearing hearing protection doesn’t work here as it can protect your ears but not your baby’s. According to CDC, pregnant women, who work in noisy circumstances, should either get a pregnancy leave or request to work in a quieter ambience.

2. Consume Fish That Have Low Mercury

Mercury is not good for your growing baby. It can lead to birth defects including hearing loss. So, you must avoid having fish containing high mercury such as tilefish, swordfish, shark, and king mackerel.

You can have fish like tilapia, salmon, shrimp, and cod, as they have low mercury levels. Fish should be a part of your pregnancy diet chart as they provide essential Omega 3 fatty acids, an important nutrient for the brain development of your baby. But you need to check the mercury level of the type of fish you are having. Always speak to your doctor or nutritionist before consuming fish during pregnancy.

3. Be Careful of Your Medicines

Some medicines have an adverse effect on the hearing ability of your baby. So, inform your gynaecologist about all the other medicines you take for your blood pressure, diabetes, or dental problems. Tell your doctor to prescribe safe medication for pregnancy.

[Read : Garbh Sanskar During Pregnancy and its Health Benefits]

What Are the Key Stages of Baby’s Hearing Development?

Here is a chart of key fetal development stages of baby’s ear and hearing in a womb.

You will have to show special care for your baby’s hearing and avoid loud sounds as soon as you reach your second trimester. And for good practice of hearing, you can play a soothing melody or rhyme repeatedly when pregnant. Your baby will keep it in memory and recognise it afterwards.

[Read : Will Listening To Music Make My Baby Smarter?]

FAQ’s

1. Can You Tell if a Baby Will be Deaf in The Womb?

During the third trimester ultrasound by measuring fetal motion in response to sounds or other auditory evoked testing fetal hearing ability can be tested. According to NCBI, the advanced antenatal diagnosis can detect profound sensorineural hearing loss of the fetus.

2. What is the First Thing a Baby Hears in The Womb?

The first thing that your baby hears is your heartbeat and all the other sounds that your body produces. This can be the gurgle of your stomach or the sound of wind entering and leaving your lungs.

3. Can My Baby Hear Me Shouting?

Shouting or yelling can be very dangerous for your baby’s ears. It can lead to permanent damage to hearing. The mental health of the mother also affects the pregnancy. So you should always try to remain calm and happy during pregnancy.

Read Also: Fetal Development – Know Everything About Your Baby’s Arms, Legs, Fingers and Toes