The Mother of Communication

Mother’s Day brings to mind the importance of moms in our lives, but most of us have no idea that their influence on one of the most important things we’ll ever do—speaking—begins well before we are born.

Listening in the Womb

Though some rudimentary aspects of hearing begin earlier, research suggests that the auditory system—comprising the outer and inner ear as well as the auditory nerve—becomes fully developed by around 26 to 28 weeks of gestation.

Mom's tummy can be a noisy place.

Source: Marjon Besteman/Pixabay

So, what exactly do babies hear in their mother's belly? Inside the body, they hear mom’s heartbeat, breathing, and digestive noises. From the outside world, the most prominent and consistent sound they’re exposed to is their mother’s voice, along with occasional music or other environmental sounds.

Because of the insulating properties of the womb and amniotic fluid, the range of sound babies can hear is limited to mainly lower frequencies. This means that elements of speech like pitch and rhythmic patterns are what prenatal babies are most able to detect.

This early exposure to a mother’s voice helps begin a special communicative bond between mother and child. In fact, studies have shown that when babies in utero hear their mother’s voice—played through a loudspeaker placed on the mother’s belly—their heart rate increases, a sign of recognition and engagement. When they hear an unfamiliar female voice, their heart rate decreases.

An Outsized Influence

What’s fascinating is that this early exposure to a mother’s speech appears to prime babies for language learning—a process that begins even before birth.

The limited frequency range of the womb may actually serve a protective and preparatory purpose. It allows babies to tune in to the rhythm, tone, and prosody of speech without being overstimulated by the full complexity of language sounds. This limited speech exposure seems to help babies begin distinguishing between native and non-native speech patterns, and may even aid in recognizing emotional cues in voices.

This early experience gives newborns a kind of “starter kit” for language. Once born, they’re better prepared to take on more complex tasks like identifying vowels, consonants, and other unique characteristics of their native language.

It’s somewhat similar to how vision develops: newborns start out seeing the world in a blurry way, giving their visual systems time to adjust. With speech, though, the training begins in the womb, setting the stage for rapid learning after birth.

Research shows that, soon after birth, babies already distinguish and show a preference for their mother’s voice over a stranger’s. They can also tell the difference between a familiar language and a foreign one, even when both are spoken by someone they’ve never heard before.

Preparing to Speak

Not only does prenatal exposure to speech help babies recognize language patterns, but it may also begin to build the physical foundations for speaking.

Ultrasound studies have observed that fetuses move their mouths in response to vowel sounds, appearing to mimic the mouth movements needed to produce those sounds. This suggests that early exposure to speech may help establish sensorimotor pathways—the neural circuits linking hearing and movement—that will later support speech production.

Forging a Linguistic Bond

Hearing a mother’s voice also appears to play a crucial role in a child’s cognitive, emotional, and social development.

For example, research has shown that premature babies in neonatal intensive care units (NICUs) benefit from hearing their mother’s voice—even if they aren’t able to be held. This auditory exposure can help them feed more effectively, gain weight, and become more socially engaged.

One study found that premature infants who hear their mother’s voice regularly show greater conversational behaviors and go on to have higher language development scores at both 7 and 18 months of age compared to those without that exposure.

Full-term infants, too, show a clear preference for their mother’s voice, which suggests that beyond helping with language development, her voice also soothes and strengthens the bond between mother and baby.

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For instance, hearing a mother’s voice has been linked to increased oxytocin levels, the hormone associated with social bonding, especially when the voice includes emotional or supportive cues. One study found that girls undergoing a stressful experience had lower cortisol (stress hormone) levels and higher oxytocin after talking to their mom—but not after texting. The sound of her voice made the difference.

A Lasting Connection

As it turns out, a mother’s voice is not just comforting—it’s foundational. It’s the first sound we come to recognize, the first rhythm we grow familiar with, and the first step in our journey to understanding and using language.

This Mother’s Day, as we reflect on everything moms do for us, it’s worth remembering that their role as our first teacher starts long before we enter the world. Even in the womb, their voices help shape who we are—cognitively, emotionally, and linguistically.