Why is spread of current in cochlear implants a problem?

Current spread leads to poor spectral resolution even in implants with smaller and more numerous electrodes. In addition, the similarity in transimpedance values recorded across the four implants suggests that electrode array design did not significantly affect amplitude with the biphasic pulses used.

What is the frequency range of cochlear implants?

70-350 Hz
In the Medel cochlear implant a frequency range can be set from 70-350 Hz up to3500- 8500 Hz. It is logical to assume that there is best frequency range for speech perception.

How do cochlear implants work basilar membrane?

Cochlear implants bypass the eardrum, the ossicular chain, the basilar membrane, and the (usually dead) hair cells. They stimulate the auditory nerve fibers with electrical pulses delivered from electrodes implanted inside the cochlea, as shown in figure 2. (Courtesy of Cochlear Ltd.)

How does the cochlear implant work?

Unlike hearing aids, which make sounds louder, cochlear implants do the work of the damaged parts of the inner ear (cochlea) to provide sound signals to the brain. The electrode array stimulates the hearing nerve, which then sends the impulses to the brain, where they are interpreted as sound.

How many electrodes stimulate the cochlea with a cochlear implant?

Fidelity 120 generates 8 channels per pair of electrodes. 16 electrodes have 15 pairs, so 15*8 = 120. Cochlear’s implant has 22 electrodes, with one current source (two, if the positive source and the negative source are counted separately, as MED-EL counts) shared among all of the electrodes.

What is pulse width cochlear implant?

Pulse-width. It is the duration of the phase of the biphasic wave of each pulse, expressed in microseconds (μs), which translates as the amount of time that the stimulator provides electric current in every phase of an impulse.

Which part of the cochlear implant digitizes the electrical signal?

The coil transmits the digitized information across the skin to the internal receiver/stimulator (e). The internal receiver/stimulator decodes the incoming signal and sends information in each frequency band to a different electrode within the cochlea (f).

What does a cochlear implant converts sounds into?

A cochlear implant transforms sounds into electrical signals and transmits these signals directly to the auditory nerve of the inner ear, bypassing any damaged structures in the ear that are impeding normal hearing.

Are cochlear implants removable?

Cochlear implants are small electronic devices that provide sound to people with significant or profound hearing loss. The main difference is they are surgically implanted under the skin behind the ear instead of being removable. …

Why are cochlear implants controversial MI?

Why is a cochlear implant so controversial? Expensive procedure, may result in complete hearing loss, and is offensive to the deaf community.

Where are cochlear implant electrodes placed?

The internal components; the receiver-stimulator, and the electrode, are surgically placed behind the ear, and the electrode is placed within the cochlea, respectively. The external components are worn much like a hearing aid, and consists of a microphone, processor and transmitter.

What are cochlear implant electrodes made of?

The surface materials that meet these stringent requirements and are currently used in cochlear implants mainly are platinum for the electrode contacts, silicone for the coating, and titanium for the casing.