Hearing begins to develop during the second trimester at about 18 weeks gestation. By the third trimester, the fetus responds to auditory stimulation. This is why by the time babies are born they have had extensive access to the general rhythm and intonation of the language in their environment, and therefore show a preference for their mother’s voice. Yep. Mom is the favorite, it’s science!
Hearing is essential for speech recognition and comprehension, which is why it is a concern for SLPs. The Newborn Hearing Screening is administered so any hearing impairment can be detected. If hearing loss goes undetected, the child can fall behind their same aged peers in the areas of language, cognitive, and social skills.
Not every state mandates Newborn Hearing Screenings. Unfortunately, this means that some newborns leave the hospital with undetected hearing loss. Only 95% of babies are screened within 1 month of birth. The screenings are not painful for the baby at all, and can even be performed while the baby is asleep. The video below shows how the screenings are conducted.
As the video points out, the screening test done in the hospital soon after birth can only detect hearing loss at the 35 dB (decibel) level. Here is a list of the different levels of hearing loss that can be found:
26-40 dB = mild loss
41-55 dB = moderate loss
56-70 dB = moderately severe loss
71-90 dB = severe loss
91+ dB = profound loss
So this means that the hospital screening does not have the capability of detecting mild hearing loss. This is why a supplementary hearing test should be administered especially if there is a family history of hearing loss.