Can a Baby Hear Outside Noises from Inside the Womb?

Your baby can hear you — even from inside your womb. From the sound of your voice, the gurgles of your digestion and your gasps of air to thunder, barking dogs and other loud, startling noises in your home, your baby can make sense of a lot of the outside world. Although some of the noise is muffled by amniotic fluid, you should exercise caution if you work or are frequently in a loud environment. The doctor will check your baby's hearing when she is born, however, you feel comfortable playing soothing music and singing to your developing baby.

Hearing in Fetal Development

The bones and tissue that make up your baby's ears are in place by the 16th week of gestation. By 24 weeks, they're complete. Around this time, babies in utero can blink and be startled by stimulation. Perception of sound matures as your baby develops. Your baby will go from being startled by noise to be stimulated by them. Eventually he will be able to recognize and distinguish some of them. In addition, the volume of the sound required for your baby to hear and respond gets progressively lower until 42 weeks, when his hearing will be as keen as an adult's.

Noises Startle and Soothe

At some point during your second trimester, you'll begin to notice your baby's reacting to certain noises. When a familiar voice comes around, like Dad's or Grandma's, she may poke or kick, an indication she recognizes the voice. According to the AskDrSears website, your baby may jump at the sudden onset of sound, so if you drop a pot or go to a concert, your baby should react at this stage of development 2. From six months onward, your baby's sense of awareness of the world outside the womb grows exponentially. This is because her brain cortex is developed enough for thinking. The AskDrSears website states that your baby has a discriminating ear at this point; she may kick violently in response to loud, thumping rock music, but may be calmed by smooth, classical tunes 2.

Babies Make Sense of Noises

Not only can developing babies identify and respond to them, but you can also use noises to teach your baby when to kick, according to the AskDrSears website 2. Researchers made a loud noise, which stimulated the babies, and the babies kicked in response to the stimulation. Researchers then placed a vibrator on the mother’s abdomen right after the noise. Then, researchers stopped making the loud noise, but still placed the vibrator on the mother's belly. The babies still kicked, even though they no longer heard a sound, but only felt the vibration. In addition, researchers reporting in the September 1994 issue of "Archives of Disease in Childhood," your baby's growing sensitivity to sounds as he matures may promote language development later on 3.

When to Be Concerned

Dr. Gerard M. DiLeo, an obstetrician and gynecologist writing on, says most babies, even those exposed to Mardi Gras while in the womb, usually don't develop hearing problems as a result of being exposed to loud noises. However, he says, you should err on the side of caution and avoid prolonged exposure to loud noises. If your job demands it, your baby should be checked for noise-induced hearing loss. Sometimes, the hearing problems could develop later in childhood and repeated exposure to loud noise can affect your baby in other ways. Children who had high-frequency hearing loss between the ages of 4 and 10 were more likely to have been born to women who worked in places with loud noise, according to the American Academy of Pediatrics 1. In addition, the AAP reports some evidence exists that such exposure may be related to congenital anomalies, increased risk of pre-term delivery and low birth weight.