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?

Week of pregnancy Development
4–5Cells in embryo start to arrange themselves into baby’s face, brain, nose, ears, and eyes.
9Indentions appear where baby’s ears will grow.
18Baby starts to hear sound.
24Baby is more sensitive to sound.
25–26Baby responds to noise/voices in the womb.

The early forming of what will become your baby’s eyes and ears begins in the second month of your pregnancy. 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 their 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.

As your baby grows, more sounds will become audible to them.

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. They will respond with an increased heart rate that suggests they are more alert when you’re speaking.

As for classical music, there’s no evidence that it will improve a baby’s IQ. 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.

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
  • meningitis
  • 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, 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 breastfeeding or bottle-feeding
  • calm down or smile when you speak to them
  • recognize your voice
  • coo
  • have different types of crying to signal different needs

From 4 to 6 months, your baby should:

  • track you with their eyes
  • respond to changes in your tone
  • notice toys that make noise
  • notice music
  • make babbling and gurgling sounds
  • laugh

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 them
  • understand a few words (“water,” “mama,” “shoes”)
  • babble with noticeable groups of sounds
  • babble to get attention
  • communicate by waving or holding up their 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 time frame, consult with your doctor.