In the United States, all babies are screened for hearing loss at birth. Permanent hearing loss at birth is relatively uncommon, occurring once in every 1,000 births. The loss may be linked to genetic predisposition, a congenital disease, or maternal disease during pregnancy. More subtle hearing impairments may be detected at a later time. Post-birth hearing losses may also occur. These are often caused by undiagnosed middle ear infections, brain infection (e.g. meningitis), brain trauma, or damage to the auditory nerve. Even a large amount of ear wax may cause moderate hearing loss which may cause language and speech delays that are often not detected until much later in childhood.
Mild to severe hearing impairment is very common, with 2 in 100 school-aged children affected. All children are screened as they enter school. However, if a child’s hearing loss is detected at this point, speech and language abilities may have already been delayed or impaired.
The ability to distinguish individual parts of speech (called phonemes) and hear the "melody" and rhythm of talking (called prosody) comes with the experience of hearing. A mild to severe hearing impairment can inhibit a child’s ability to mimic speech and become fluent in a language. Babies’ brains begin to develop the ability to recognize their parent’s voices within the first couple of months of life. Any hearing impairment in early childhood may delay or inhibit language development.
As early intervention is key to remediating a speech-language delay, a parent may look for signs that a baby or young child is experiencing partial or full hearing loss.
In babies, such signs include:
- Not reacting to loud sounds. An absence of a startle response or crying after a loud noise. After 6 months of age, not turning to look for the source of the noise.
- Delayed speech, for instance, not saying “mama, papa, or dada” by their first birthday.
- Does not recognize own name when called.
In young children these signs include:
- Sitting very close to the television, radio, or iPad to be able to hear it.
- Seems to hear some sounds but not others.
- Hears and/or responds to your voice when calling from another room.
- Any sign of delayed speech development.