As pregnancy progresses, many women speak to the babies growing in their wombs. Some mothers-to-be sing lullabies or read stories. Others play classical music in an effort to boost brain development. Many encourage their partners to communicate with the baby, too.
But when can your baby really begin to hear your voice, or any sound from inside or outside of your body? And what happens to hearing development during infancy and early childhood?
Fetal Hearing Development: A Timeline
|Week of Pregnancy||Development|
|4-5||Cells in embryo start to arrange themselves into baby’s face, brain, nose, ears, and eyes|
|9||Indentions appear where baby’s ears will grow|
|18||Baby starts to hear sound|
|24||Baby is more sensitive to sound|
|25-26||Baby responds to noise/voices in the womb|
The early forming of what will become your baby’s eyes and ears begins in weeks four and five of your pregnancy, according to the American Pregnancy Association. That’s when the cells inside the developing embryo begin arranging themselves into what will become the face, brain, nose, eyes, and ears.
At roughly 9 weeks, little indentations in the side of your baby’s neck appear as the ears continue to form on both the inside and the outside. Eventually, these indentations will begin moving upward before developing into what you’ll recognize as your baby’s ears.
Around 18 weeks of pregnancy, your little one hears his very first sounds. By 24 weeks, those little ears are rapidly developing. Your baby’s sensitivity to sound will improve even more as the weeks pass.
The limited sounds your baby hears around this point in your pregnancy are noises you may not even notice. They are the sounds of your body. These include your beating heart, air moving in and out of your lungs, your growling stomach, and even the sound of blood moving through the umbilical cord.
Will My Baby-to-Be Recognize My Voice?
As your baby grows, more sounds will become audible to him or her.
Around week 25 or 26, babies in the womb have been shown to respond to voices and noise. Recordings taken in the uterus reveal that noises from outside of the womb are muted by about half.
That’s because there’s no open air in the uterus. Your baby is surrounded by amniotic fluid and wrapped in the layers of your body. That means all noises from outside your body will be muffled.
The most significant sound your baby hears in the womb is your voice. In the third trimester, your baby can already recognize it. He will respond with an increased heart rate that suggests he is more alert when you’re speaking.
Should I Play Music for My Developing Baby?
As for classical music, there’s no evidence that it will improve a baby’s I.Q. But there’s no harm in playing music for your baby. In fact, you can continue with the normal sounds of your daily life as your pregnancy progresses.
While prolonged noise exposure may be linked to fetal hearing loss, its effects aren’t well-known. If you spend a lot of your time in an especially noisy environment, consider making changes during pregnancy to be safe. But the occasional noisy event shouldn’t pose a problem.
Hearing in Early Infancy
According to KidsHealth, about 1 to 3 of every 1,000 babies will be born with hearing loss. Causes of hearing loss can include:
- premature delivery
- time in the neonatal intensive care unit
- high bilirubin that requires a transfusion
- certain medications
- family history
- frequent ear infections
- exposure to very loud sounds
Most children born with a hearing loss will be diagnosed through a screening test. Others will develop hearing loss later in childhood.
According to the National Institute on Deafness and Other Communication Disorders (NIDCD), you should learn what to expect as your baby grows. Understanding what is considered normal will help you determine if and when you should consult a doctor. Use the checklist below as a guide.
From birth to around 3 months, your baby should:
- react to loud noise, including while breast- or bottle-feeding
- calm down or smile when you speak to him
- recognize your voice
- have different types of crying to signal different needs
From 4 to 6 months, your baby should:
- track you with his eyes
- respond to changes in your tone
- notice toys that make noise
- notice music
- make babbling and gurgling sounds
From 7 months to 1 year, your baby should:
- play games like peek-a-boo and pat-a-cake
- turn in the direction of sounds
- listen when you’re speaking to him
- understand a few words (water, mama, shoes)
- babble with noticeable groups of sounds
- babble to get attention
- communicate by waving or holding up his arms
Babies learn and develop at their own pace. But if you’re concerned that your baby isn’t meeting the milestones listed above in an appropriate timeframe, consult with your doctor.