A baby develops the ability to hear sounds at about 18 weeks into the pregnancy, according to MayoClinic.com. The uterus, though snug and warm, is not soundproof. In fact, your baby can hear — and respond to — a wide range of sounds, from those your body makes to sounds outside your womb.
Your baby’s ears and earlobes start to form when you are about eight weeks pregnant, but it takes another three months at leas) until your baby can start picking up sounds. By the time the third trimester begins, your baby’s ears are fully functional, and the range of sounds she can hear greatly increases.
Your baby can hear your heart beat (the sound is, in fact, as loud as a vacuum cleaner to a fetus), the blood whooshing through your veins and your stomach growling. He can also hear noises from your environment, such as the television, music, and most importantly, your voice.
Babies react to the sounds they hear in the womb. They jerk when they are startled by a loud noise, and research shows they recognize their mother’s voice even in utero, according to “Psychology Today.” In fact, your baby’s heart rate actually slows down when she hears your voice, which means she is already soothed by your particular tone — even before she is born.
There’s an old wives’ tale stating that if you play classical music for your baby before he is born, he will become smarter. This is known as the “Mozart Effect,” but there is no scientific evidence to back it up, according to BabyCenter. Still, it won’t hurt him, and you may even make him a fan if you continue to expose him to classical music after he is born.
Ultrasounds are a way to check on the progress of fetal development, but they also create a loud sound in the uterus, according to NewScientist. In fact, the sound is as loud as a subway train arriving at a station. For this reason, experts suggest that ultrasound probes be aimed away from the ears of a developing baby.