When can baby hear your and your partner's voices – and should you talk, read or play music to her? Read on to learn everything you need to know about your baby's developing sense of hearing during pregnancy.
It’s only natural that as you get used to the idea of the baby growing inside you, you might start talking to her, crooning lullabies and encouraging your spouse to chat with your belly. It’s not all in vain — beginning in the second trimester of pregnancy, your baby can detect sounds from outside your body. The voices, tunes and noises she hears in utero do, in fact, help her get used to the environment she’ll enter at birth.
When hearing develops
Around week 6 of pregnancy, even though your little embryo is still smaller than a pea, the cells inside her developing head are already beginning to arrange themselves into unique tissues that will eventually be her brain, face, eyes, ears and nose. Although you can’t distinguish ears on an ultrasound yet, the complex maze of tubes that make up the inner ears are starting to pinch off from the rest of the cells inside the head. By week 9, small indents will appear on the sides of the your baby’s neck — although they’re not in their final location yet, they will gradually move up and become the tiny, curled up, cute-as-a-button ears that you’ll gawk over when your baby is born.
Throughout your first and second trimester, your baby’s ears continue to develop: The inner ear connects with neurons in the brain responsible for processing sounds, and the miniscule bones of the middle ear (which sense the vibration of sound waves) form. Around week 16 of pregnancy, it’s likely that these structures are well-established enough for your baby to start detecting some limited noises. Some of these are sounds that you might not even notice yourself — the gurgle of your stomach and whoosh of air in and out of your lungs. Over the next few weeks though, your baby will hear more and more of the outside world. By week 24, babies have been shown to turn their heads in response to voices and noises.
What does it sound like in there?
Sounds travel best through open space — you can hear someone yelling more easily in an open field than when your head is underwater in a pool, for instance. And your baby isn’t exposed to open air when she’s still growing inside you – there’s amniotic fluid surrounding her, plus all the layers of your body and their amniotic sac, between her and the world. So even when her ears are fully developed, the sounds she hears in utero are muffled.
Try this for fun (really!): Put your hand over your mouth. Have your partner do the same. Then carry on a conversation – and that’s what voices sound like to your baby in the womb. You’ll notice that although you can make out the tones and pitches of a sentence, you might not be able to understand some words. Similarly, try singing a song with your mouth covered and you’ll hear that the tune comes out loud and clear, but not the lyrics.
The louder a sound, of course, the more likely your baby can hear it. A barking dog, honking horn or wailing siren is going to sound more distinct than quiet background music — but that’s not necessarily a bad thing. The sounds your cutie gets used to in utero will be less likely to startle her after she’s born.
Mother’s voice is clearest
When you’re pregnant, the clearest noise your baby will be able to make out is yours. While most sound is transmitted through the air — and then through your uterus, when you speak, the sound of your voice reverberates through your bones and the rest of your body, amplifying it. Studies have shown that a fetus’s heart rate increases when she hears her mother’s voice, suggesting your baby becomes more alert when you speak. So reading out loud, carrying on conversations and singing the songs you’ll be repeating to your baby over the coming years will help her to get to know your voice.
But don’t despair, Dad — babies also learn to recognize other voices (including yours!) and sounds that they hear often in utero. Researchers have discoveredthat newborns react differently to words and sounds that were repeated daily throughout the third trimester compared to those they never heard during pregnancy. And from inside the uterus, it turns out that deeper, lower sounds are easier to make out than high-pitched ones. So when you read or sing to your baby, she’s learning your voice!
How you can support baby's hearing in utero
So what should you do to make sure your baby’s hearing develops normally? Should you play classical music through headphones pressed against your belly? Should you avoid rock concerts? In most cases, just carrying on with the sounds of normal life is best. There’s no reason to avoid a loud situation — whether it’s a concert you’ve been anticipating for months or an especially raucous baby shower.
Noise does have the possibility to cause some developmental damage or hearing loss in a growing baby when it’s loud, prolonged and repeated. So if you work on a noisy factory floor for eight hours a day, for example, it's worth talking to your boss about the possibility of transferring temporarily to a quieter setting.
You might have heard that playing classical music to your baby in the wombcan boost his or her IQ or give her a foundation for a better education — but there’s no proof that this is the case. That said, there’s also no harm in putting on your favorite tunes — whether they’re classical sonatas, honky tonk country or rock and roll. Your baby might just learn to love the music.