In 2001, the Oregon Legislature passed a law mandating that all infants born at birth centers with more than 200 births a year had to have a hearing screening prior to leaving the hospital. Smaller birthing centers had to provide information to families on where they could get a free screening. Prior to this law, the average age of identification of childhood hearing loss was approximately 2 ½ years. Since the law’s inception this has dropped to under 6 months. Clearly this has been a great advancement in treating childhood hearing loss.
When we think about hearing loss, we tend to focus on children with severe to profound hearing loss. In fact, due to their overt lack of responses to sound, children with severe to profound hearing loss were identified at a relatively young age. It was those children with mild hearing loss, high frequency hearing loss and unilateral hearing loss that went unidentified, often times not till over 5 years of age. Due to their late identification, children in these categories often times had significant delays in communication, socialization, and academics.
Part of the problem is our perception of the terminology used to classify hearing loss. We classify hearing loss by degree, normal, mild, moderate, severe, and profound. If we look at this terminology in another context we can get a different perspective. Imagine your at a picnic and get involved in a softball game. The next day your arm is sore and you go to the doctor and you are diagnosed with a mild sprain. You think nothing of it, no big deal, and it goes away in a week or so. The same applies to hearing loss, as a parent you hear the word mild and you think “not a big deal”. This is supported by observing your child. Your child startles to sound, turns to their name and is even acquiring a few words.
But, the mild hearing loss is nothing to be ignored, it can have significant impact on a child’s development.
What is a mild hearing loss?
That depends? In adults, normal hearing is from 0-25dB. However, at OHSU for children, normal hearing is between 0 and 15dB. Most children have hearing at 0dB or even better. A mild hearing loss would be hearing levels between 15 and 35-40dB. To get an appreciation of what this means, we need a reference point. Our reference point is the level of “normal” conversation. This is approximately 45dB. So a child with normal hearing, let’s say 10dB, listens to normal speech, 45dB, that is a 35dB “dynamic range”. Now our child with the mild hearing loss, 30dB, and the signal stays the same, 45dB, that child only has a 15dB dynamic range.
What is the impact of mild hearing loss?
To answer this question let’s look at the child with the 30dB hearing loss. With speech coming in at 45dB, this child will hear speech at a much softer level than a child with normal hearing. The impact of this will be most noticeable as we increase the distance from the speaker to the child, and when we talk to the child in a noisy environment. The result of this will be a delay in speech, language, and conceptual development. Some of these may include, omission of grammatical markers such as the /s/ at the end of a word that signifies plurals or possessions; delay in the use of past tense markers like /ed/ ; and what we might call “garbled speech”.
What can be done for children with mild hearing loss?
The most important measure to take for children with mild hearing loss is the fitting of hearing aids. Unlike children with severe or profound hearing loss, children with mild hearing loss will receive immediate and noticeable benefit from properly fit amplification. Like children with more severe hearing loss, children with mild hearing loss should be enrolled in an early intervention program that focuses on the use of listening to develop spoken language.
Children with mild hearing loss should continue to have their hearing evaluated as it is not unusual for hearing loss to be progressive. During the first year, hearing should be evaluated every three months.
After one year hearing should be evaluated every 6 months or at the recommendation of the audiologist. At a minimum, all children with hearing loss should have yearly hearing assessments.
The benefits of the newborn hearing screening program in Oregon is that we are now identifying children with all degrees of hearing loss from mild to profound. This allows us to work with families to initiate appropriate intervention. Through this intervention program all children with hearing loss regardless of degree can have access to information that will allow for the development of spoken language.