Electrode of cochlear implant is placed at ?
Ans. is 'c' i.e., Scala tympani Aural rehabilitation devices Hearing-impaired individuals may be helped by aural rehabilitation devices. The devices may be : ? 1. Hearing aids These are miniaturized sound amplifying devices to amplify sounds reaching the ear. These devices contain a microphone to recieve sound, an electronic processor (amplifier) that manipulates the qualities of sound to make it more usable to listner, a speaker (receiver) that conves electrical impulses back to the sound. Hearing Aids may be of two types : ? Air conduction hearing aid : - In this, the amplified sound is transmitted the ear canal to the tympanic membrane. Bone conduction hearing aid : - Instead of a receiver, it has a bone vibrator which snugly fits on the mastoid and directly stimulates the cochla. This type of aid is specially useful in persons with actively draining ears, otitis externa or atresia of the ear canal when ear-inses cannot be worn. Hearing aid is indicated in persons who has a hearing problem that cannot be helped by medical or surgical means. 2. Implants Two commonly used Implants are : ? A. Cochlear implants Cochlear implants bypass the function of the sensory receptors by directly stimulating ganglion cells in the auditory nerve. Cochlear implants conve the mechanical sound energies into the electrical signals that can be directly delivered into the auditory nerve in severe or profoundly hearing impaired individuals. Cochlear implant has two components : External component : - It contains microphone, speech processor and transmitter, and remains outside the body. Internal component : - It contains receiver/stimulater which is implanted under the skin and electrode which is implanted in the Scala tympani of the cochlea a cochleastomy opening in the basal turn of cochlea. It may also be placed at other locations like promontory or round window but these sites has poorer performance. B. Auditory brainstem implant The cochlear nucleus complex within the brainstem is stimulated directly by placing the electrode into the lateral recess of fouh ventricle. Such implant is used when V///'h cranial nerve has been severed in surgery of acoustic neuroma. Cochlear implants are not effective in this situation.
Horizontal semicircular canal
Scala media
Scala tympani
Scala vestibuli