There are lots of products on the marketplace that suggest playing music to your unborn child is beneficial. But is it safe to put headphones on a woman’s pregnant belly?
Placing headphones on a pregnant belly is not only unnecessary, but it can also be harmful. Recommendations are that normal hearing experiences in the womb are sufficient for normal fetal auditory development and sound devices (including headphones) should not be directly placed on a pregnant woman’s abdomen.
Fact 1: Babies Can Detect Subtle Nuances of Sound Without Intervention
A baby’s auditory system comes online at about 16 weeks. It is functional and they are hearing and interacting with their environment (and beyond – the mother’s environment) from then. They can hear and process all types of sound, even the subtle nuances of speech.
In studies of babies 1 – 3 days old, they have tested for neural response to language of their native tongue (both spoken and recorded and play normally and backwards) and that of other languages. They clearly showed neural responses to intricate subtle changes in their native language above all other sound.
When tested 3 feet away from an ear in quiet conditions, language sits between 30 – 60 decibels. In the womb, the sound would be muffled and quieter naturally because of the fluid so if a baby in the womb can adequately hear between 30 – 60 decibels in muffled conditions and react to subtle nuances in speech, putting any sound source directly onto the mother’s belly could do harm.
Fact 2: Babies in Utero Do Not Have Auditory Filters
A fetus does not have the filters that we have in place as adults (or older children). Filtration systems are formed after birth – in fact months after birth so you are dealing with an infant that brings in all sound equally (including that in his/her environment).
Because they are processing sound all the time (between the mother’s heartbeat and her own body sounds, sounds in the environment and their own heartbeat) while music can be beneficial, there is no need for headphones on the mother’s belly.
All sound (even though muffled because of the amniotic fluid) is processed adequately without any additional resources. So why the need for headphones? In fact, it is a much more natural experience to process sound in the womb as the mother moves to music that is in her environment. This has the additional benefits of the vestibular system.
Fact 3: Sound is Processed Two Ways
When we process sound, we not only process through our ears, but it is also a whole-body experience with vibrations and sound being processed through our skeletal system as well. It is no different for preterm babies.
When we process through our ears it is called air conduction. When we process through our skeletal system it is called bone conduction. Have you ever wondered why your voice sounds different when you hear it recorded? That is because when we speak, we are processing our voice with both air and bone conduction.
When we hear a recording, we are primarily hearing it through air conduction and so it sounds incredibly different.
Because the fetus is in a fluid filled environment, processing through the body (bone conduction) is more prevalent. That means their whole body is used in the process of interpreting sound – every sound. Too much stimulation is tiring (as it is after they are born too).
Fact 3: Sound Exposure That is Too Loud Can Produce Premature Births
Research has proven that sound exposure that is too loud can produce premature births and even a reduction in birth weight.
While the occasional loud sound is not harmful, prolonged sounds above 85 dB have been proven to be in the harmful range for adults. For children, lower thresholds are recommended.
Examples of sounds and their loudness are:
| Sound | Measurement in dB |
| Normal breathing | 0 – 10 |
| Leaves rustling, whisper | 30 |
| Average home noise | 40 |
| Normal conversation, background noise | 50 |
| Vacuum cleaner | 70 |
| Window air conditioner, power lawn mower, heavy traffic, noisy restaurant | 80 – 89 |
| Subway, shouted conversation | 90 – 95 |
| Boom box, motorcycle | 100 |
| Leaf blower | 106 – 115 |
| Rock concert, loud symphony | 120 – 129 |
Fact 4: Manufacturers of Fetal Headphone Products Do Not Do Scientific Research and Testing
Many websites of fetal music products including headphones to place on the mother’s belly, state that they are “proven safe.” Tow did they test it? What do they use to test it?
Has there been a study of a sizable number of babies where they have tested this exposure both pre and post birth? Have they followed any differences in the subsequent first couple of years of life?
What standard are they testing against? Most use charts of safe sound levels for adults but that does not give an indication of what is safe for a fetus.
Fact 5: Testimonials Are from Users Who Don’t Understand the Implications
In testimonials on many of the website for these types of products, there are many that say when they first play the music their baby kicks or reacts which take that as a sign that they are enjoying it and listening.
Overstimulation in a fetus can produce the same movements. A baby in distress with also move and kick when presented with challenges. Too much sound or damaging sound will make a fetus kick and move because it is uncomfortable for them. It is up to adults to ensure that babies in the womb are protected from prolonged loud sounds.
Fact 6: Many Quote Sources for Adults, Not Preterm Babies
Many manufacturers state what safe level for babies are according to the CDC and NIOSH. The maximum recommended safe sound level for pregnant women is around 75dB according to these sources. This is equivalent to a noisy restaurant or a vacuum cleaner. (Source: CDC and NIOSH).
The CDC and NIOSH are the regulators for hearing loss prevention in the workplace and set the ground rules for what is acceptable. They are not specialists who have done trials on unborn infants and the effects of sound. It is like comparing apples and oranges.
Fact 7: Babies Need to Process Speech
Babies need to process speech. In a study in 2011, they proved that neural organization in the language centers of the brain happens prior to birth because of the processing of language in the womb. If parents are playing music through headphones on a mother’s belly, the sound would drown out the ability to hear and process the nuances of speech.
More is being put into the sound space than baby needs. With less time to process language, there is no telling what effect that will have on the ability to process speech and language after birth. It could also lessen the brain organization benefits because less time is spent processing language. Putting competing sounds into an unborn baby’s environment exposes them to less sound processing experiences and potentially less brain connections.
Fact 8: You Can’t Argue with the Research
There was a study done in 2000 that started the research into fetal sound processing. It was ahead of it’s time at the time. In 2012, another study took things a step further (with the advancement of technology and testing equipment) specifically into the effect sound has on preterm infants and fetuses. There are others, but this is the most significant.
The Sound Study gave the following recommendations:
The Sound Study Group’s recommendations for the fetus were as follows:
1) women should avoid prolonged exposure to low-frequency sound levels (<250 Hz) above 65 dB during pregnancy
2) sound devices, including earphones, should not be directly placed on a pregnant woman’s abdomen
3) programs to supplement the fetal auditory experience (e.g., such as playing music) are not recommended since the voice of the mother and normal sounds of the mother’s body are sufficient for normal fetal auditory development (Graven, 2000).
Fact 9: Babies Have Immature Auditory Filters
We all have auditory filters in place to zone out unimportant auditory input. These filters develop with opportunities to develop our 13 essential auditory skills. Some of these skills enable our auditory system to filter out unwanted or unimportant sounds to make things less exhausting.
Adults have the most advanced auditory skills/filters because they have had the longest to develop them. Younger children have more immature skills with babies having the most immature auditory skills of all.
Pre-birth, these filters are not in place and so all sound comes in at the same level. Children on the spectrum can have the same challenge. When we “hear” a dog barking up the street while we are asleep, our system recognizes that it is not an essential sound and does not alert the brain.
When we hear our baby crying in the middle of the night, we wake, no matter how tired, because our filtration system sees that as an essential sound, alerts the brain and we wake up.
Imagine if every sound you heard came in at the same volume. Fans, the hum of computers, dogs barking, traffic, babies crying etc, it would be exhausting.
We need to protect our pre-born baby’s hearing because they don’t have those systems in place to weed out certain sounds. This can keep the brain on overdrive as it tries to make sense of all the auditory input.
Putting headphones on a pregnant woman’s belly might seem like a good idea, and from a marketing standpoint, it looks great, but when you understand the scientific data and the implications, it is not only unnecessary but should be avoided.
