Hearing loss occurs when ear abnormalities, illness or injury cause a reduction in a child’s ability to detect or process sounds. The loss of hearing that results may be mild, moderate, severe or profound. Problems with hearing are among the most common major abnormalities in babies, according to the American Academy of Pediatrics (AAP).

Hearing loss is either congenital (present at birth or shortly thereafter) or acquired (occurs sometime after birth). It may involve deficits in detecting a range of pitches (high and low sounds), and/or a range of intensities (loud to soft sounds). There are three major types of hearing loss:

• Conductive hearing loss. Occurs when a blockage or structural problem interferes with the process of sound transmission in the outer or middle ear. In most cases, this type of hearing loss is mild and disappears when the underlying condition is treated with medication or surgery.
  
  
• Sensorineural hearing loss. Occurs when the noise signal is transmitted from the outer to the middle ear, but is not properly converted and interpreted by the brain. Malformation, dysfunction or damage to structures in the inner ear, such as the cochlea or hearing nerves, can be causes. In most cases, this type of hearing loss is permanent.
  
  
• Mixed hearing loss. Occurs when hearing loss is a result of both conductive and sensorineural factors.

Hearing loss is most likely to have profound consequences on normal speech and language development when it occurs during infancy and toddler years. Abnormalities in the ear and illness (such as an ear infection) are the most common causes of hearing loss at these ages. Treatment of a child’s hearing condition by 6 months of age is crucial to avoid these deficits. As children enter the adolescent years, injuries and exposure to loud noises become the greatest risk to their hearing.

Hearing loss may come on suddenly, or it may progress slowly over time. The severity of hearing loss varies greatly. Some children may be able to detect certain sounds, but may have trouble hearing others. Other children may have a complete loss of hearing known as deafness.

Hearing loss can be very difficult to diagnose in children who are not yet old enough to speak or to fully express themselves. Hearing problems in babies are most likely to be found during screenings that are routinely performed on children soon after birth. As children grow older, it may become easier to detect signs of hearing loss. Children who appear to have a hearing loss should visit a physician to receive a formal diagnosis.

In many cases, a child’s hearing loss is a temporary symptom resulting from a condition that is highly treatable. However, some forms of hearing loss are more likely to be permanent. In such situations, early treatment with devices such as hearing aids or cochlear implants is crucial to a successful long-term prognosis. Children with hearing loss and their parents can learn American Sign Language to communicate without words.

Most cases of hearing loss – including those caused by a birth defect or illness – are not preventable. However, certain steps can be taken that may reduce the risk of hearing loss.