Information About Deafness
- Of 236 million people in this country over the age of 3, about 20 million have some degree hearing loss.
- One infant in 22 is born with, or soon develops, a hearing loss.
- Hearing impairment that starts in childhood or later may be caused by:
- Diseases, especially in young children (German measles, meningitis, cytomegalovirus)
- Noise (jet engines, industrial noises, loud music, rifle fire)
- Drugs (certain antibiotics and diuretics)
- Nearly 5 million cannot hear normal speech.
- Otitis media (middle ear infection), the most common cause of hearing loss, costs an estimated $1 billion a year.
- Communication disorders -- including disorders of speech and language as well as of hearing -- carry an estimated $30 billion a year price tag in special education costs, medical costs, and lost productivity.
The Human Factor
Helen Keller felt her hearing loss was more devastating than her blindness because it isolated her from people rather than from things.
For older adults, loss of hearing may be just one of many losses to endure, and the isolation can be particularly devastating.
Hearing aids don't necessarily "fix it"; lip-reading is difficult to learn and not precise; sign language is even more difficult to learn and not likely to be known by friends and family.
For the very young, hearing impairment and deafness can interfere with one of the major tasks for which the child's brain is primed: learning language. We know that language is more easily learned before the age of five than later; that children who are deaf have a harder time learning a spoken language; and that language acquisition is necessary for most other learning.
What We Know Now and How It Helps
- We can now identify hearing impairments at birth.
- We can distinguish between hair cell and nerve deafness (and therefore fit appropriate hearing aids).
- Some of today's hearing aids are normally able to compensate for outer hair cell loss.
- We can identify the genetic basis of some hearing impairments.
- Today's cochlear prosthesis, or implant -- an electronic substitute for damaged or lost hair-- cells is more sophisticated than the earlier versions and is now approved for both children and adults for whom hearing aids are useless.
Teaching Materials on Hearing Physiology
- Dick Bobbin's Lecture
- Dick Bobbin's Auditory
- Physiology Text
- Neurotransmission in the Cochlea
- Pentobarbital on MOC induced suppression of DPOAEs
Links to Other Web Sites on Deafness
Universite Montpellier, France, Promenade autour de la cochlee
Johnathan Ashmore's laboratory on hair cell physiology
Johns Hopkins' site with a bias towards biomedical engineering
The Unversity of Wisconsin's site on cochlear function and motion of the organ of Corti
House Ear Clinic
Specializing in Information ior the Deaf and Hard of Hearing
A listserve of parents whose children have auditory neuropathy
More updates on auditory neuropathy/dys-synchrony from a parent
National Cued Speech Association
Demo of what speech might sound like to an auditory neuropathy patient
Alexnader Graham Bell Association for the Deaf and Hard of Hearing
American Academy of Audiology
Association for Research in Otolaryngology
American Speech and Hearing Association