Can fetuses hear

When Can a Fetus Hear: Womb Development Timeline

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Medically reviewed by Debra Sullivan, Ph. D., MSN, R.N., CNE, COI — By Jessica Timmons on January 4, 2018

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?

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.

Last medically reviewed on January 5, 2018

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2nd Trimester

How we reviewed this article:

Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Blackburn S. (2013). Maternal, fetal, and neonatal physiology. (4th ed.). Seattle, WA: Saunders.
Fetal development: Stages of growth. (2014).
my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth
Hearing evaluation in children. (2016).
kidshealth.org/PageManager.jsp?dn=KidsHealth&lic=1&ps=107&cat_id=192&article_set=22902
Mayo Clinic Staff. (2017). Fetal development: The second trimester.
mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151
Pierson LL. (1996). Hazards of noise exposure on fetal hearing [Abstract]. DOI:
10.1016/S0146-0005(96)80054-1
Your baby’s hearing and communicative development checklist. (2010).
nidcd.nih.gov/health/hearing/pages/silence.aspx

Our experts continually monitor the health and wellness space, and we update our articles when new information becomes available.

Current Version

Jan 5, 2018

Written By

Jessica Timmons

Edited By

Nizam Khan (TechSpace)

Medically Reviewed By

Debra Sullivan, PhD, MSN, RN, CNE, COI

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Medically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI — By Jessica Timmons on January 4, 2018

When can a fetus hear? Everything you want to know

People often wonder if a fetus can hear while in the womb. Many expectant parents will speak to or play music for a developing fetus.

Evidence suggests that the auditory system starts forming at the 18th week of pregnancy and continues to develop until the baby is between 5 and 6 months of age.

Everything that the fetus hears will contribute to this process. In this article, we look at what a fetus can hear at different stages of development.

Share on PinterestA fetus will develop their ability to hear while in the womb.

Despite being close to a lentil in size, an embryo will begin to develop ears during the 2nd month of pregnancy. The ears start as tiny folds of skin on the sides of the head. After the 8th week, the embryo becomes a fetus.

According to Mayo Clinic, the ears begin to stick out from the head at 18 weeks, and the fetus may become able to hear. At this stage, the brain starts to designate the areas that will govern smell, taste, vision, touch, and sound.

By 22 to 24 weeks, the fetus will be about the size of a mango and will start to hear low-frequency noises from outside of the womb.

As the fetus grows and their sense of hearing develops, they will be able to distinguish an increasing number of different sounds.

Research suggests that the most vital time for the development of hearing is between 25 weeks of pregnancy and 5 to 6 months of age.

By the time babies reach the age of 6 months, they will be able to turn their eyes or head toward the source of a sound.

Newborns in the United States usually receive a hearing test before leaving the hospital or within 3 weeks of birth.

At first, a fetus cannot distinguish between different voices.

A fetus begins responding to sound at between 22 and 24 weeks but can only hear low frequencies, such as a dog barking or a lawn mower.

As the auditory system and the brain continue to develop, this range increases. By late pregnancy, the fetus can hear voices and distinguish between them.

Many people wonder whether it is safe to attend a loud concert or work in a noisy job while pregnant. While occasionally hearing loud sounds is unlikely to be harmful, research has found that prolonged exposure to loud noises may contribute to hearing loss in the baby.

Examples of noisy jobs include those that involve people working in close proximity to:

loud music
crowds
sirens
trucks
airplanes
machinery
guns

According to the National Institute for Occupational Safety and Health, researchers are unsure of what noise levels are safe for a developing fetus.

However, taking into consideration how sound travels through the body, they recommend that pregnant women avoid very loud situations — anything louder than 115 decibels, which is about as loud as a chain saw — as much as possible.

Share on PinterestA fetus can benefit from hearing speech and music.

The noises that a fetus hears from around week 23 of pregnancy are vital to their future hearing.

Specific parts of the auditory system need these noises to develop properly. As such, scientists recommend exposing a fetus to both speech and music.

Many people believe that playing classical music to a growing fetus will help brain development and boost IQ, but there is little evidence to support this claim.

It is noisy in the womb. As the fetus’s auditory system develops, it will encounter all types of sound from within the woman’s body. These include the heartbeat, as well as the noises of the blood flow and digestive system.

Around the 23rd week of pregnancy, the fetus will also be able to hear noises from outside of the womb. These include speech and music. As the fetus develops, all of the sounds will become louder and more distinguishable.

Amniotic fluid surrounds the growing baby in the womb, and the woman’s body tissues encase them, so noises from outside the body will sound muffled.

The ears of a fetus start to develop relatively early in pregnancy. However, hearing does not develop until the auditory system, the brain, and certain pathways start to form, which usually occurs between weeks 22 and 24.

The auditory system requires stimulation through speech, music, and other sounds to grow properly. As it does, the fetus will be able to hear more and more.

A baby’s hearing continues to develop after birth, until around 5 or 6 months of age.

When does a baby in the womb begin to hear?

Even in the mother's womb, the baby begins to hear sounds, react to them, and even distinguish the voices of loved ones.

When does a baby begin to hear its mother in the womb?

You don't know your baby yet and you can only imagine what he will be like when he is born. The child begins to get to know you by voice even during pregnancy. Around the 12th-16th week, the baby begins to distinguish sounds, and at the 24th week it can respond to the voices of mom and dad. nine0003

Of course, the first person he is a baby is his mother. Until the child's auditory canals are formed, he can feel the vibration of your voice passing through your body, as well as your breathing and heartbeat. In the last trimester, he is already extracting some information from voices and sounds, demonstrating various reactions. What exactly the baby hears and how often you need to talk to him - read on.

How about different voices?

Your baby can hear and recognize the voices of the people around you all the time. He is already familiar with his dad's voice. The child may prefer some voice that is pleasant to him. If the voice (or any other sound) is too harsh or loud, the baby may react to it with strong jolts. nine0003

Hear music?

Do you know that the music that a child hears in the womb through the neuroendocrine system affects almost all systems and organs of the child? Depending on the type and tempo of the music, the respiratory rate, muscle tone, motility of the stomach and intestines of the baby change. Avoid loud and harsh music, let your baby listen to the classics: Mozart and Vivaldi. Calm music can even lull the baby.

How often should you talk to your child? nine0005

Of course, you need to talk to your baby as often as possible - both mom and dad. Take every opportunity to talk to your baby. Talk to yourself when you do something around the house or walk.

Scientists have proved that when hearing the voices of parents, the child reacts to their intonation and calms down, the rhythm of his heart returns to normal. Therefore, the tone of conversation should be calm, voices should be quiet. Children who constantly hear the gentle voice of their mother are born calm and balanced. nine0003

Sing songs

Sing songs to your baby. Soon you will notice that the baby can react to them - actively move.

Talk to the baby

If you already know the sex of your child, address him by the name you have chosen for him. Or come up with an affectionate nickname for the baby.

Read aloud

Read books to your baby. It can be any literature: children's or adult's that you like. If you read before bed, read aloud. This habit will come in handy when your baby is born. nine0003

Avoid noise

Try to avoid noisy places, harsh sounds and loud conversations. If the baby does not like something, he may begin to push hard.

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© Nutriclub, 2020

What a baby can learn before birth

Leslie Evans Ogden
BBC Earth

19 July 2016

Image copyright, Science Photo Library

The cuttlefish already knows how to recognize its prey before it emerges from the egg, and the newly hatched chick already knows the "password" to interact with its parents. All this suggests that the training of the baby begins even before birth, the observer is sure BBC Earth .

When I was pregnant with my first child, unsolicited advice rained down on me like a waterfall. Most expectant mothers are familiar with this phenomenon firsthand. "Do not eat spicy", "No garlic, especially when you are breastfeeding."

But, being a lover of spicy dishes, I was skeptical about these recommendations and did not become cautious. After all, there are so many different gastronomic traditions in the world. Surely in countries whose cuisine is unimaginable without spicy dishes, babies somehow get used to the special taste of breast milk? nine0003

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On my part it was nothing more than idle reasoning, but my small and completely unscientific experiment with just one subject confirmed their correctness.

Seeing with what pleasure the baby sucks milk with a touch of Thai curry and garlic, and then requires more, I never doubted that he was used to these products even before he was born. More serious research also suggests that taste preferences are formed in babies while still in the womb. nine0003

Moreover, prenatal learning is not limited to taste and is not exclusively a human ability. Experiments show that animals of various species, both large and small, learn about the world even before they are born, studying tastes, smells, sounds, and even sights available to them before birth.

Image copyright Thinkstock

Image caption

Babies are sensitive to the taste of breast milk

So can you learn to love garlic in the womb? This question also interested Professor Peter Hepper from Queen's University Belfast. nine0003

Together with his colleagues, he conducted a study of 33 children whose mothers either ate garlic frequently or did not eat it at all in late pregnancy.

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Despite its small scale, this study yielded surprising results: Garlic addiction persisted in children for several years. Children whose mothers preferred garlic dishes during pregnancy enjoyed eating garlic potatoes even when they were eight or nine years old. nine0003

So how do human babies recognize the taste of garlic while in the womb? There are several possible answers to this question.

First, Hepper explains, a baby can get a taste by swallowing amniotic fluid. This usually occurs from the tenth week of development. Thus, he can taste the taste that food gives to the amniotic fluid.

Second, taste can be transferred directly from the mother's blood to the baby's blood, bypassing the digestive system. nine0003

This is especially true with garlic, which can linger in the body for several hours after eating it. That is why if you eat garlic, its smell will be felt even the next day. At the same time, the gastronomic preferences of the baby are influenced not only by products with a pronounced, but also with a rather weak taste.

Image copyright, Getty Images

Photo caption,

Garlic and chili have a distinct flavor

In a study sponsored by a baby food company, scientists at the Monell Chemical Irritant Research Center in Pennsylvania, USA observed for infant response to carrot-flavored and neutral-flavored foods. nine0003

Some of the mothers drank carrot juice and water during the last trimester of pregnancy and the first months of breastfeeding, others only water.

After analyzing the facial expressions of five- and six-month-old babies when taking these two types of food, scientists came to the conclusion that babies could fall in love with carrots in the womb, swallowing amniotic fluid with the taste of this vegetable, or after birth, eating breast milk with a similar taste .

Such conclusions may seem pseudo-scientific, but in fact they are not. In general, in mammals, taste and smell appear to be important factors initiating the feeding process. nine0003

"When a baby is put on the breast, he feels the same taste that he was used to in the last 30 or more weeks before birth," Hepper says. "If the taste is different, problems can arise."

It is not surprising, then, that taste training in the womb is widespread among mammals. This phenomenon is typical for rabbits, rats, dogs and cats. This mechanism may have evolved as a way to protect offspring from dangerous foods. It can also help babies get to know their mother. nine0003

"It's very important for cubs," Hepper says, "to be able to recognize who is naturally programmed to take care of them."

Image copyright, Getty Images

Image caption,

Lynx with calf

These systems of recognizing their mothers before birth are of particular importance to certain bird species that other birds, such as cuckoos, may lay their eggs on for hatching.

So, for example, a painted malur often becomes a victim of deception by the red-tailed bronze cuckoo. Having seized the moment, the cuckoo lays its eggs in the nest of the painted malor, but prenatal training can help the malur to sense something is wrong. nine0003

Diana Colombelli-Negrel of Flinders University in Adelaide, Australia, says she was able to detect this behavior "by pure chance".

During her research on predators, she recorded around the clock the sounds coming from the nest of beautiful painted cyaneus (Malurus cyaneus).

Later, listening to these recordings, she discovered that while incubating the eggs, the females made a special call. This behavior of the expectant mother, who seemed to be supposed to be quiet so as not to attract the attention of predators, seemed strange to her. nine0003

Intrigued by this question, Colombelli-Negrel compared the mother's cries during incubation to the cries of later hatched chicks begging for food. Their resemblance was striking.

Could mothers "talk" to chicks before they were born, to teach them the characteristic call that hatchlings make when they are hungry?

Photo copyright, David Tipling

Photo caption,

Beautiful painted malurus (Malurus cyaneus)

To test this conjecture and prove that the calls of chicks, similar to those of their mother, are not just a genetic program that has nothing to do with prenatal training, Colombelli-Negrel and her colleagues conducted a cross-nurturing experiment. nine0003

They swapped the eggs of different birds to determine whether the cries of the chicks would be more similar to those of the mother or the adoptive mother.

It turned out that the chicks made sounds more reminiscent of the voice of the bird that hatched them, and not of their biological mother. So scientists were able to confirm their hypothesis that chicks are able to hear and remember sounds while inside the egg.

As Colombelli-Negrel co-author Mark Hauber of Hunter College, New York, explains, the researchers also measured changes in the heart rate of developing chicks inside the egg to see if they could learn to distinguish between different kinds of sounds. nine0003

According to Hauber, this confirmed that "the embryo learns while in the egg, even before it is born." Next, the scientists set out to find out if parents are able to notice subtle differences in the cries of chicks.

They studied the response of adult birds in the nest to recordings of the calling calls of their own chicks, chicks from other nests, and the calls of the Red-tailed Bronze Cuckoo chicks. Representatives of this species of cuckoos sometimes throw their eggs into the nests of painted malyurs, which can unwittingly take them for their own. nine0003

This can turn out to be a real disaster for the little ones, because the hatched cuckoo chick usually throws all the other chicks out of the nest, dooming them to death so that it gets all the attention of its parents.

However, it was not so easy to deceive the painters. They responded more actively to the cries of their own chicks, bringing them more food. Thus, it can be concluded that at the moment, the malurae manage to maintain an advantage in confrontation with the cuckoos, teaching the voice password to the unhatched chicks. nine0003

"The password is their ticket to life," says Hauber. "If the chick doesn't say the password, the parents will give him less food" or leave the nest altogether to start over.

The results of a recent study by Colombelli-Negrel, Hauber and colleagues show that the red-backed painted tambourine - a close relative of the beautiful painted tambourine - is also able to teach its chicks vocal signals during brooding.

Now scientists are wondering how widespread this phenomenon of early learning is. They are not the first to become interested in this topic. Back at 19In the 1970s, Gilbert Gottlieb noticed that ducks also resorted to prenatal training.

In a later paper, Christopher Harshaw and Robert Lickliter of Indiana University describe the results of their experiment based on the ugly duckling story. They found that if unborn and incubated Virginia grouse chicks were played a recorded call of a Japanese quail, they would subsequently prefer it to those of their own species.

image copyrightDavid Welling

Photo caption,

Virginia partridge (Colinus virginianus)

Unfortunately, other than these researchers, few people have so far shown interest in studying the ability of embryos to recognize sounds and learn them.

Nevertheless, scientists have not bypassed the prenatal perception of sounds by representatives of one particular species.

Are infants' sound preferences innate or acquired? Apparently, people have a combination of both. nine0003

New York University psychologist Athena Vouloumanos was interested in the developmental stage at which a person begins to learn a language. Determining whether a fetus is able to perceive speech is quite difficult, she explains.

That is why scientists study babies and look at what sounds they heard before they were born to find out how this will affect their further development. Voulumanos compared the response of newborns to human speech and to other sounds.

image copyrightThinkstock

Image caption,

Playing music to a baby in the womb is unlikely to produce results

Babies spend a lot of time sleeping, "but at this stage it's vital for them to learn to suck."

Therefore, in order to distinguish between the acquired in the womb and the innate sound preferences of babies, a team of scientists led by Voulumanos decided to test their sucking reflexes.

They used nipples with built-in pressure sensors, specially designed to measure the intensity of suckling. nine0003

When a baby is actively suckling on a sterile pacifier, certain sounds are played, explains Voulumanos.

"The harder he sucks, the more sounds he hears - it's called positive feedback," she says. By changing the sounds that babies hear, she found that they begin to actively suck on the pacifier when they hear the sounds of human speech.

Experiments have shown that the preference for speech sounds over non-speech ones [they can be heard by clicking on the links] in newborns is most likely congenital, not acquired. nine0003

Nevertheless, scientists have found that newborns recognize the sounds of their native language and listen to them with great pleasure - this can only be learned.

"Children of English-speaking parents were more likely to suck on the pacifier at the sounds of English speech than in French," says Vouloumanos. "And the children of French-speaking parents made more effort when they heard French, which the experimenters interspersed with Russian."

They are able to recognize the sounds of their native language not only from their mother's lips, but also when other people speak. nine0003

In addition, Voulumanos' colleague Janet Werker of the University of British Columbia found that children of bilingual parents (who spoke both English and Tagalog) responded similarly to both mother tongues.

What about music? Can a fetus remember melodies while in the womb?

Image copyright, Thinkstock

Image caption,

Babies can learn to suck harder on a pacifier to hear pleasant sounds

A group of Finnish scientists conducted an experiment in which a group of women in late pregnancy listened to a baby lullaby almost every day " Twinkle Twinkle Little Star The second group did not listen to this melody. nine0003

After the birth of the children, the researchers tested each child's response to small changes in tune or "mistakes" in a familiar tune.

"During the experiment, the children were sleeping," says Minna Huotilainen of the University of Helsinki, who led the study. "To determine their reaction, we used an encephalogram, that is, we recorded a continuous signal coming from different parts of the brain."

The brains of children who listened to a melody even before they were born responded more strongly to both correct and incorrect notes, compared to children to whom it was not played before. This allows us to conclude that they learned and memorized the melody while still in the womb. nine0003

The study turned out to be very fruitful, as scientists were able to find out how important it is to pay special attention to the sound environment of preterm babies.

Image copyright, Thinkstock

Image caption,

A child is capable of learning even at the earliest stages of development

If there is a lot of mechanical noise in the maternity hospital, babies will remember these sounds instead of speech sounds. "This can lead to language learning problems later on," says Huotilainen. nine0003

Huotilainen is currently studying preterm babies carried in baby carriers by their mothers. The subjects are divided into several groups: those who do not listen to anything, those who listen to speech, and those who listen to quiet lullabies. With this experiment, she is trying to find out how certain sounds can affect the development of the speech abilities of babies.

Eino Partanen, a master's student under Huotilainen and co-author of her research paper on prenatal music learning, also hopes to find out how, when and what sounds we learn, and "what developmental deficiencies we can correct in infancy." nine0003

However, Huotilainen is skeptical about the idea of artificially simulating the sounds that a fetus should hear in the womb.

She questions the usefulness of "fetal stimulants" - devices designed to play music directly to the baby in the womb. Some of them are mounted on the stomach, and some of these devices are even equipped with vaginal speakers.

"I'm not at all sure that such devices are worth using," she says. nine0003

Photo copyright, David Fleetham

Photo caption,

Pharaoh cuttlefish (Sepia pharaonis) eggs

Animals' ability to learn during prenatal development is not limited to the tastes, smells and sounds around them.

While studying cuttlefish, which have to forage immediately after birth, Ludovic Dickel became interested in whether they can see anything while in the egg, and how this affects their preferences.

According to him, baby cuttlefish have "one of the richest behavioral repertoires in the animal kingdom, and it's a dream for a behavioral biologist." nine0003

His research with other colleagues showed that about three weeks before leaving the egg, as soon as the visual system begins to function in cuttlefish, they can see what is on the other side of the egg, and thus gain certain knowledge.

In fact, for them, the egg is the same as the womb is for human babies, only with a transparent wall.

In one experiment, Dickel and his colleagues showed cuttlefish embryos images of crabs so that no chemicals they produced could give away their smell or taste. Once out of their eggs, these cuttlefish ate crustaceans with greater pleasure than their relatives, who lacked visual cues prior to birth. nine0003

In addition, Dickel's team found that even earlier, four weeks before hatching, cuttlefish can have a rewarding experience of touch and chemical cues, such as the scent of a predator like the European sea bass.

The ability to learn to smell danger is also found in salamanders and frogs. Knowing how safe the environment they will encounter at the very beginning of their life can be very important for these amphibians.

Many of them, such as the ringed ambystoma (Ambystoma annulatum), develop in drying waters, often infested with predators, and 90-99% of the young die before turning from tadpoles into adults.

That's why, says Alicia Mattis of the University of Missouri, applying what they learn before they're born can save their lives.

"They have to work very hard to survive," says Mattis, "and therefore they are surrounded on all sides by chemicals that contain comprehensive information about the outside world," including what other species live in the reservoir. nine0003

Image copyright, Visuals Unlimited

Photo caption,

Ambystoma annulatum (Ambystoma annulatum)

There are years when the body of water is quite safe, and you can freely leave the shelter in search of food.

"But there may come a year when there will be plenty of predators around, including salamanders that don't mind feasting on members of their own species," says Mattis.

Thus, those babies who can assess the risk of being eaten immediately after birth and behave accordingly have a greater chance of survival. nine0003

That's the kind of early chemistry lesson Mattis plans to teach to the endangered Allegheny brambles.

To increase the numbers of these amphibians, they are bred in captivity.