Development of Hearing in Fetuses and Babies

Fetal Development: Around the 20th week of pregnancy, the fetus begins to hear very low-frequency sounds, primarily those generated within the mother's body, such as her heartbeat and digestive sounds.

Increased Sensitivity: By the 24th to 27th week, the fetus can start to respond to external sounds and might even be startled by loud noises. It's around this time that many expectant mothers notice reactions when they play music or when a loud noise occurs.

Birth: At birth, babies can hear, but they're more sensitive to high-frequency sounds. Over the first few months, a baby's hearing will continue to improve, and they will start to turn their head toward familiar sounds, such as a parent's voice.

Maturation: Even after birth, the auditory system continues to mature. Newborns primarily respond to pitch and rhythm, while the ability to discern finer details of sound, like speech, continues to improve over the first few years of life.

It's worth noting that the in utero environment is conducive to the development of hearing, as it's filled with various sounds. This is one of the reasons why many parents-to-be talk, sing, or play music to their unborn child, helping to stimulate auditory development and foster early bonding.

Remember, every individual develops at their own pace, and the above milestones are general guidelines. If there are concerns about a child's hearing or auditory development, it's essential to consult with a pediatrician or audiologist.