deafdude1

Mapping for Dummies

Lots of good information and facts about hearing, hair cells and CI mapping. Here's an excerpt:

The cochlea is actually a shell shaped cavity within the bone of the skull It's about as big as your baby finger tip from the nail up. The oval window (the opening in the cochlea connected to the ossicles (the three bones in the middle ear space) is vibrated, which sends a wave through the cochlea. There are thousands of tiny hair cells in the cochlea - all in rows. There are two different types of hair cells in the cochlea, named for where they are in the row - inner hair cells and outer hair cells. If you can imagine stretching out the two and a half turns of the cochlea, the hair cells are organized along the length of the cochlea like keys on a piano. The part nearest the oval window is called the "basal" end of the cochlea, and the part farthest from the oval window is the "apical" end. Just like a piano keyboard, different parts of the cochlea are designed to receive different frequencies/pitches. The "basal" end vibrates better with higher pitches, and as lower pitches are received, more "apical" parts of the cochlea are vibrated. The hair cells are like seaweed floating in the fluid of the inner ear. When the part of the cochlea they reside in vibrates, the hair cells bend and that triggers a small natural electric impulse which is connected to the auditory nerve. The inner hair cells send the information and the outer hair cell around it works as a natural amplifier. They emphasize peaks of information received along the cochlea. The outer hair cells are the first hair cells to be damaged when there is a sensorineural loss. They help people to hear sounds below 60dB and allow for some fine tune discrimination of frequencies. The outer hair cells emit a sound when they are provoked and when they are resting. In a test called "evoked otoacoustic emissions" a microphone in the outer ear looks for small but measurable sounds that the outer hair cells generate when the cochlea is healthy. These emissions are not found in children with conductive or cochlear based hearing losses worse than 30 dB. So, if a child who responds as profoundly deaf has otoacoustic emissions, the problem is probably past the cochlea.

__________________

Deafness

__________________
This advertising will not be shown in this way to registered members.
Register your free account today and become a member on AllDeaf.com