So far we have read that the gestational baby develops its hearing between (approximately) weeks 14 and 16; Y This allows you to hear internal sounds such as the heartbeat and blood flow.. We also knew that from week 27, the ear is fully formed, babies are able to perceive sounds external to the mother's body; according to this study echoed by SINC, the auditory cortex reorganizes and the nervous system matures, and this served as a basis for exploring prenatal experience based on the perception of sounds and the modeling of neural bases.
However, until now I had no record of any study with the characteristics and conclusions of this one that I now present to you: the Marqués Institute (Assisted Reproduction Clinic, Gynecology and Obstetrics in Barcelona), has published in the journal British Medical Ultrasound Society, a world-pioneering research on fetal hearing. They have discovered the formula for them to hear like us, so that The sound reaches them efficiently in intensity and with less distortion.
But how is that if the uterus is soundproof?
Well, vaginally, yes, as you heard: a speaker is placed in the vagina, so that the fetus is able to hear (almost) with the same intensity as the music is emitted. Since the vagina is a closed organ, sound is not dispersed., and in this way the sound does not have to pass through the abdominal wall, only the vaginal and uterine walls.
This research confirms that babies listen from week 16 of gestation; bear in mind that until now there were many doubts about the functionality of the already formed ear
Participants in the study were pregnant women between 14 and 39 weeks of gestation. The reaction of the fetus to hearing music has been observed by ultrasound, emitted both abdominally and vaginally; and results have been compared by emitting vibrations (without music) from the vagina.
What does the fetus do when it listens to music?
First of all, clarify that the music chosen to carry out the study was that of Johann Sebastian Bach (La Partita in A. Minor for Flute Alone - BWV 1013)
Normally, when awake fetuses spontaneously move their heads and limbs; they also stick out their tongues. But the music induces a response of vocalization movements by activating brain circuits to stimulate language and communication, from which it follows that learning begins in the womb. The baby's response to music is specific movements of the mouth and tongue, as can be seen in the following video:
https://www.youtube.com/watch?t=58&v=e0Cpz1eUF5Y
What do you hear in the womb?
In the intrauterine environment they are mainly perceived low and rhythmic sounds: the mother's heartbeat and blood flow, bowel movements, breathing, and her voice filtered through tissues and amniotic fluid. Mid and low frequencies are transmitted better than high frequencies, and the volume is attenuated through the abdominal wall, the uterus, and the amniotic fluid. Therefore, music reaches the outside with less clarity; when a vaginal transmitter is used, the signal passes through fewer barriers and intelligibility increases.
This internal soundscape is not unimportant background noise: trains the auditory system developing and prepares the brain to recognize patterns of rhythm and intonation, key to human speech. As gestation progresses, the fetus moves from reflex responses to increasingly more organized and specific to certain stimuli.
The scientific study: prenatal musical exposure and brain imprinting
In addition to the work of the Marqués Institute, other groups have analyzed how the daily exposure to music during pregnancy It leaves a measurable mark on the newborn. Research with healthy newborns, comparing babies exposed to music for more than half an hour a day versus babies with occasional exposure, has recorded the so-called frequency-following response (FFR), an auditory evoked potential that reports on the neural encoding of speech sound.
The results show that consistently exposed newborns present greater amplitude in the encoding of the fundamental frequency (F0) of speech stimuli, regardless of the type of syllable used to elicit it. This more robust coding of low-frequency components is related to a better tuning of the auditory system for tone, a relevant ability for later language acquisition.
Possible limitations include the retrospective evaluation of musical exposure (with risk of recall bias) and uncontrolled variables such as maternal stress or hereditary components of musical-linguistic skills. Even so, the consistency of the findings suggests that early neuronal plasticity is sensitive to the prenatal acoustic environment, whether through music played through loudspeakers or songs sung by the mother.
What important innovations does this study bring?
The work of the Marqués Institute introduces a key innovation: the vaginal route as an effective channel to transmit sound to the fetus with sufficient intensity and low distortion, allowing specific responses to be observed vocalization (mouth and tongue movements) across a wide range of gestational ages. In parallel, research with FFR provides a neurophysiological correlate that explains why these motor responses could be linked to auditory-linguistic networks in maturation. Together, these lines of evidence help us understand that music during pregnancy is not just an anecdote: modulates circuits involved in communication and attention to speech.
Another novel contribution is the comparison between different types of music. Although there is no universally superior “single style,” different rates of orofacial movements have been observed to classical, popular, Christmas carols, solo vocals, or marked rhythmic patterns. This suggests that certain acoustic characteristics (steady rhythm, moderate tempo, clear melodies, energy spectrum in low frequency bands) could facilitate the fetal response more than “gender” itself.
Study applications
- It is shown that fetuses hear from the week 16 of pregnancy.
- Allows you to discard the fetal deafness.
- Mom can ascertain fetal well-being.
- We discovered primitive brain circuits involved in communication. Upon hearing music, the fetus responds with vocalization movements, a step prior to sing and speak.
Beyond these observations, current evidence points to complementary uses: strengthen the emotional bond (talk, hum and sing to the baby), reduce maternal anxiety and cortisol with relaxing music and potentially employ measures such as neonatal FFR as early biomarkers in language risk detection to facilitate targeted musical interventions. Important: There is no evidence that music increases intelligence of the baby; what is observed is a more favorable environment for the auditory processing and well-being.
How does a baby perceive music and how does he react to it?
Although the fetus is surrounded by amniotic fluid, uterus and abdominal tissues, can perceive sounds from outside, with some distortion. Several experiments have shown that with speakers on the belly or through vaginal emission the sound arrives more clearly, and the fetus reacts with gestures such as opening the mouth or sticking out the tongue. These responses, observed by ultrasound, are compatible with network activation brain cells involved in language.
Changes have also been documented in fetal heart rate and motor activity patterns to certain musical stimuli, as well as the newborn's ability to recognize melodies repeated during pregnancy (prenatal memory), which helps calm them after birth and establish sleep routines.
Practical recommendations and safety
- Prioritize your well-being: Choose music that relaxes you and that you enjoy. The benefit comes, in large part, from the maternal emotional response that the baby shares.
- Moderate volume: Avoid high levels and prolonged exposure; aim for comfortable intensities (home environment), without forcing.
- Duration and timing: 20 to 30 minute sessions, especially in Late night when it is easier to relax.
- Type of music: soft instrumental, moderate tempos (approx. 60–80 beats per minute), warm voices, and clear melodies. Singing or humming is an excellent and safe option.
- Devices: external speakers at a comfortable volume or experiences of maternal songAvoid invasive solutions or internal use without medical supervision.
- Ultrasounds: Ultrasound exposure should be clinical and justified, avoiding its indiscriminate use or for recreational purposes.
Benefits for mother and baby
music can reduce anxiety and improve maternal mood, facilitate rest and attenuate the perception of pain in advanced stages of pregnancy. These effects, mediated by the endorphin release and stress regulation, favor the fetal well-beingIn babies, repeated exposure to specific melodies can generate postnatal recognition, useful for calming and promoting routines.
In clinical settings, it has been observed that prenatal musical stimulation may be associated with improvements in fetal cardiac parameters and with less anxiety of the pregnant woman during monitoring, without this implying direct changes in the baby's intelligence. The focus should be on the emotional well and in a stable and pleasant sound environment.
Questions that remain open
The news has surprised me and intrigued me in equal measure, I suppose like it has many other people. It has also left me with some questions that I hope to resolve one day; for example, I understand the potential applications of such an experiment, but I'd like to know if there are any possible risks, and if they are justifiable by the benefits. I also wonder if Nature may have wisely planned for the soundproofing of the uterus (as it should have been). So it won't hurt to make babies listen to music so closely?Of course it depends on the type of music.
On the other hand, let's not forget that the ear canal of children is small, and that causes a difference in the amount of decibels they perceive, compared to adults. They are also more vulnerable because their skull is thinner.
I also allow myself to remember that prolonged exposure to ultrasound energy (in this case, the ultrasounds that are done to check the reaction of babies), it is associated with different risks, if the technique is used indiscriminatelyThe investigation is still active to further define what acoustic characteristics favor orofacial responses, how they relate to neonatal FFR, and how we might leverage this sensitivity to prevention and support in language development, always under safety criteria.
Current evidence indicates that the fetus hears and reacts to music from an early age; the vaginal route allows for the observation of specific responses with less distortion; daily musical exposure leaves a measurable imprint on the voice coding of speech; and, above all, that the greatest benefit comes when the mother enjoy, relax and connect with your baby through sounds and songs, taking care of volume and timing.