Signs and causes of hearing loss in children

Learning to hear and listen

To better understand hearing loss in children, it is important to understand how a child learns to hear and listen and the communication milestones for their age.

After birth, a newborn baby’s hearing is similar to an adult’s, but babies must learn how to use their hearing to form the foundations of communication. They need to hear the sounds of their language repeatedly so they can associate sounds with words. They also learn to listen and experience the world by associating sounds to things. Whether it’s the sound of water running at bath time or a soothing lullaby when it’s time for sleep.

Localization

One of the earliest and easiest auditory skills to observe in your baby is localization – the ability to pinpoint the source of a sound. Because we hear through two ears (binaurally), we can localize sounds with extreme accuracy.

Observing your child’s localization ability
In general, newborns will move or widen their eyes when they hear a loud sound. This is known as the "startle reflex" and many loud sounds should prompt this reaction. When your child is five or six months, you can better observe a true localization response by making soft sounds behind or beside them while they are looking straight ahead. A soft rattle or a whisper should prompt your baby to turn his or her head toward the sound. It is very important to see how well your baby responds to soft sounds (such as the speech sound “s“).

Speech and language development milestones

9 months – Demonstrates an understanding of simple words such as “mommy“, “daddy“, “no“, “bye-bye“.
10 months – Babbling should sound “speech like,” with single syllables put together (“da-da-dada”). The first recognizable words emerge around this time.
1 year – Speaks one or more words.
18 months – Understands simple phrases, retrieves familiar objects on command (without gestures) and points to body parts. Has a spoken vocabulary of 20 to 50 words and uses short phrases (“no more“, “go out“, “mommy up“).
24 months – Has a spoken vocabulary of at least 150 words, coupled with the emergence of simple two-word sentences. Most speech should be understandable to adults who are not with the child daily.
3 to 5 years – Uses spoken language constantly to express wants, reflect emotions, convey information, and ask questions. A preschooler should understand nearly all that is said. Spoken vocabulary grows from 1,000 to 2,000 words, which are linked in complex and meaningful sentences. All speech sounds should be clear and understandable by the end of this developmental stage.

If you notice that your child is delayed in reaching any of these milestones by approximately three months, we recommend that you have your child's hearing tested by a hearing care professional.

Signs of hearing loss in children

Always be alert to situations where your child is not responding to sound appropriately, as this may be a sign of hearing loss. Sometimes it is difficult to detect mild forms of hearing loss, including hearing loss in only one ear. It is important to remember that even mild forms of hearing loss can negatively impact a child’s ability to learn through hearing.

The most important sign of possible hearing loss is delayed development of speech and language. The following are other signs that a child may not be hearing normally:

Not aware that someone who is out of view is talking, especially when there are few distractions
Startled or surprised look when they realize their name has been called regardless of noise level
Sitting close to the TV when the volume is enough for other family members to hear
Increasing the volume of the TV or stereo to unreasonably loud levels
Not responding to voices over the telephone and/or switching ears continually
Not reacting to intense, loud sounds.

If your child is school aged, with even a mild hearing loss, they may exhibit attention, behavioral or social problems in the classroom.

Causes of hearing loss in children²

Hearing loss can be congenital (present at birth) or acquired (present after birth). Approximately 50% of all incidents of congenital hearing loss is due to genetic factors.¹ Congenital causes of hearing loss that are not hereditary in nature include

illnesses
prenatal infections
use of ototoxic medications, drugs or alcohol
premature birth
other birth complications

Hearing loss can also occur after birth, due to a disease, a condition or an injury. If you are wondering what caused your child’s hearing loss, it is best to ask your child’s physician.

Types of hearing loss in children

The primary distinction of a child’s hearing loss is made based on whether the loss of hearing comes from the inner-, middle or outer ear.

Conductive hearing loss

Hearing loss caused by an outer or middle ear problem is called conductive hearing loss. With a conductive hearing loss, the inner ear functions normally, but there is damage or an obstruction affecting the outer or middle ear, hindering sound from reaching the inner ear. Conductive hearing loss is usually temporary and treatable in children. Sounds from the outside are softer while the individual’s own voice sounds louder than normal.

Common causes of conductive hearing loss

Ear infections (otitis media) – Infections in the middle ear are the most common causes of conductive hearing loss in children. Most children will have at least one ear infection in childhood.
Ear wax (cerumen) – Wax in the ear canal can act as an ear plug, blocking sound waves from reaching the eardrum. Excessive wax may be softened with wax-softening drops and flushed out or removed by a physician or trained professional. Cotton swabs should never be used to remove impacted wax because they may push the wax deeper into the canal and could puncture the eardrum if inserted too deeply.
Swimmer’s ear (otitis externa) – Another common condition affecting the outer ear canal is called “swimmer’s ear”. This painful bacterial infection occurs when the ear canal remains wet after bathing or swimming. It can cause the ear canal to swell shut, resulting in temporary hearing loss.

Sensorineural hearing loss

Damage to the inner ear is called sensorineural hearing loss. It is caused by dysfunction of the cochlea (sensory) or auditory pathways to the brain and is often present from birth. It can also develop due to constant exposure to loud music, noise, or exposure to medication that can damage hearing. Sensorineural hearing loss is permanent and cannot be treated with medicine or surgery. In most cases, hearing aids or cochlear implants can help.

Noise induced hearing loss (NIHL) is the only type of hearing loss that is completely preventable. Sounds can be harmful when they are too loud, even for a brief time, or when they are both loud and long-lasting. It is important to ensure your child not be exposed to harmful noises by either reducing the noise, using protective devices or removing your child away from it.

Mixed hearing loss

Sometimes a combination of factors occurs that affect both the outer or middle ear and the inner ear (cochlea), resulting in mixed hearing loss.

Reference

1 American Speech-Language-Hearing Association. How Does Your Child Hear and Talk? Retrieved from https://www.asha.org/public/speech/development/chart/

2 American Speech-Language-Hearing Association. Causes of Hearing Loss in Children. Retrieved from https://www.asha.org/public/hearing/Causes-of-Hearing-Loss-in-Children/.