How does a baby’s hearing develop?

Of our five senses, hearing is the one that develops while we are still in the womb, and it develops first, so we begin connecting with the outside world very early. Hearing matters because it is how we learn spoken communication. It helps us orient ourselves, gain knowledge, learn, and it also brings experiences, entertainment and calm.

As a baby grows, their hearing becomes more refined. In the first year or two this is not only about detecting sounds, it is also about making sense of what is heard. In childhood, hearing supports learning, forming social relationships and processing information from the environment. During the school years its role becomes even stronger, since much learning happens through listening, for example explanations, instructions and discussions in lessons rely on listening skills.

In adolescence and early adulthood, it helps deepen emotional relationships, take part in community life, and communicate at work and in wider society. Even in adulthood, whether in professional or everyday conversations, good hearing is essential for effective connection and safe day-to-day life. This is why protection and regular checks matter, so we can preserve this vital ability for as long as possible.

Let us start at the very beginning.

What are the key stages of hearing development in the womb?

Did you know that in the uterus a baby first senses vibrations, then gradually begins to hear sounds from the outside world? The ear starts to develop in week 3, then goes through major changes.

After week 8 the middle ear develops, in week 11 the membrane and eardrum form. The inner ear, cochlea and cochlear duct connect to the cerebral cortex at week 21. This is when sound recognition and memory begin. Hearing becomes fully formed by week 24.

By 30 weeks, a baby can sense sounds from the mother’s body, mainly heartbeat. Sounds from outside, such as a parent’s voice, are distinguished later. If a mother talks to her baby when only her voice is present and no other sound sources are around, the little one will memorise her voice more easily and, after birth, will recognise it with visible reactions.

Because loud noise, for example machine noise or concerts, can raise a baby’s heart rate and movement, making them tense and unsettled, we should avoid these. Instead, listen more often to soothing music, meditation tracks, classical music and gentle instrumentals.

How does hearing develop after birth?

It is both interesting and natural that from the very start a baby is most captivated by the human voice and speech. They can distinguish high and low sounds, and at this stage they prefer higher ones. At first they startle at noises, later they get used to them. Sharp sounds make them jerk or cry until they realise there are always different noises around and that these are not dangerous. By one month babies already pay attention when spoken to and lower tones are calming.

Between two and four months babies gladly use their own voice, squealing playfully. They can clearly tell Mum’s voice from others. This is why it is important for Mum to talk to her baby often. By four months melodies attract more attention.

Between six and nine months hearing becomes much more refined. Babies locate sound sources from almost any direction, even from behind. They love to make noise themselves, banging, rattling and clattering. Sound-making toys are favourites. When choosing toys, make sure they do not produce distorted sounds and that they are clean and natural in tone.

At ten to twelve months little ones can become so absorbed in play that they do not pay attention to surrounding sounds. If called by name, they turn towards the speaker. For speech development, it is important that children hear themselves well, and that words from parents are clear and intelligible. If we constantly give feedback, they learn from it and better recognise the images connected to sounds.

By one and a half, hearing becomes even more refined to support understanding and the start of speech. Children love songs and music, so if you can, take them to music sessions for babies, or sing to them every day. These experiences can lay the foundations of a love for music. At this stage they mainly distinguish the melodies of higher-pitched songs. Vocabulary grows explosively.

Middle ear infections are common in babies and can become chronic. These can cause temporary hearing weakness, and if persistent, hearing loss. If you notice anything unusual related to your child’s hearing, see an appropriate specialist. What should we look out for?

• A premature baby’s reactions to sounds are not always even. Sometimes they clearly hear, sometimes they do not react. Immature nervous system development can be the reason, yet it is still worth asking a doctor for advice.

• A baby who hears well already cries differently by around six weeks to signal different needs. If hearing is poor, this does not appear. Crying is monotone, head-voiced, mechanical sounding. Cooing and babbling fail to appear.

• At nine to twelve months, it is normal for children to be so absorbed in play that they do not notice other things and do not hear when called. If this happens every time, ask a specialist for advice.

• Minimal hearing loss is not always easy to spot. Warning signs include always preferring loud toys, not seeking sound sources, lifting the head at their name yet not attending to the speaker, or making few sounds.

The ear has three parts: outer, middle and inner ear

The outer ear includes the pinna, ear canal and eardrum. In the middle ear are the malleus, incus and stapes, which transmit and amplify sound to the inner ear, where the delicate hair cells send on the signals to reach the brain. We will pause here, because there is an important point about hair cells that we must always keep in mind in today’s technologically advanced world.

Protect children from noise damage

It is very important to know that the hair cells in the inner ear are highly sensitive and vulnerable. With strong noise they can be irreversibly damaged. We therefore have a responsibility to control what volume of sound we allow for our children and for ourselves. Remember, we can rest our sight by closing our eyes, but we cannot switch off hearing, not even when we are asleep.

We can see that children need special care because they are more sensitive. Modern technology has brought carelessness in its wake. Avoid events for children that run at irresponsibly high volumes, such as concerts or very loud cinemas. What counts as a level that can already be disturbing?

Interestingly, noise can be problematic not only because of volume, but also because of its psychological effects through continuous stimulation of the nervous system. This can be noticeable above 30 dB, although not for everyone. Monotonous hums, clicking, street noise and speech fall here.

Above 65 dB, hair cells may already start to be damaged, and other autonomic and nervous system problems can occur. Sleep quality can worsen. Constant loud speech, animal noises, traffic, and the hum of machinery are around this range.

Above 85 dB, hearing organ damage occurs, with temporary or permanent hearing loss. Think of clubs, ear-splitting sirens, concerts, pneumatic drills and building works. At this point hearing protection is essential. Unfortunately, levels above 100 dB are often measured in cinemas today, even for children’s films, so parents must decide responsibly whether to expose their children to this noise hazard.

Did you know?

• The human ear can distinguish 400,000 sounds.

• In one square centimetre of the middle ear sit the three smallest bones in the body.

• Above 120 dB for example a take-off jet, we feel physical pain, and above 160 dB for example a nearby explosion or airbag deployment, the eardrum can rupture immediately, causing hearing loss.

References:

NHS — Newborn hearing screening:

RNID — How loud is too loud?