Thursday, March 24, 2011

Cochlear Implants: Part 3

Cochlear implants are not immune to technological advances. The first attempt at a cochlear implant was made by Alessandro Volta (for whom the "volt" was named). He placed metal rods in his ear canals and connected them to an electric circuit! I'm not sure I'm that brave...
Without going into too much history, I'll just say that as technology progressed, numerous designs were attempted and improvements were constantly being made to the cochlear implant...and it still continues to improve.

The latest cochlear implant design is called "The Epic," which is manufactured by Epic Biosonics. This device is going to be completely implantable--no external components! The microphone will be placed under the skin in the ear canal and the speech processor, once a big box powered by two AA batteries, will be implanted under the skin behind the ear. The design eliminates the need for a transmitting coil, as the sound will go directly from the speech processor to the electrode array in the cochlea.

The Epic will measure 3x5 centimeters and will weigh less than 3 grams--that would be roughly the size of a flash-drive (a little wider) and weighs roughly as much as three paperclips! A huge advantage to such a small and lightweight device is that it can be implanted into infants--an enormous benefit, especially in regard to speech/language development.

Other awesome advantages to a fully implantable device are that the wearer can swim, walk in the rain, takes showers, etc. without having to remove the device and go without hearing during such activities. Although these people still need to be careful about their head while physically active, they are able to participate in physical activities without having to worry about the transmitter falling off (the part that was held on by a magnet) or the processor falling out of their pocket/off their ear. The Epic is supposed to have as many as 48 electrodes (previous versions only had 16-24), which gives the wearer much clearer sound.

Finally, my favorite part about this device: the battery. There are actually two batteries: one internal and one external. The internal battery is designed to last a lifetime--no replacements needed! One concern about internal batteries was the use of liquid electrolyte, which if leaked, could be harmful. The Epic's battery, however, uses advanced technology that does not require liquid electrolyte. The battery only needs to be charged about 1-2 hours for a whole week--and this is where the external battery come in. To charge the internal battery, you use the external battery to transmit the charge across the skin using radio frequency rather that needing wires! How cool is that!!!

I currently do not personally know anyone who wears a cochlear implant (although I have in the past). But I think this device is so cool! I am always amazed at how far technology has brought us and cannot wait to see where it will go next. If anyone reading this has experiences with cochlear implants, please share by leaving a comment. For some reason, this topic fascinates me, and I would love to hear what you have to say!

Wednesday, March 23, 2011

Cochlear Implants: Part 2

So how do cochlear implants actually work?

Well, the answer to that question can get quite complicated, but I will do my best to explain it.
First, sound is picked up by the microphone (worn either behind the ear or as a clip on clothing), which as I explained in my last post, is one of the external components of the implant. Then, the sound waves are transmitted by cable to the speech processor, also an external component. In the past, the speech processor has looked like a small box that the patient has to carry in a pocket (see previous post for picture). With newer technology, however, the processors are small enough to fit on the earpiece with the microphone. The speech processor sorts and digitizes the sound into a code of electrical signals, which travels to the transmitting coil. This is the circular shaped part of the device that attaches to the skull behind the ear via magnet (illustrated on the left).
This is a picture of the electrode array.
This part is inserted into the cochlea,
which is why the array has a spiral shape.

At this point, the sound moves to the internal components of the cochlear implant via the skin by means of FM radio signal, at which point it reaches the receiver/stimulator. The receiver/stimulator is the part that contains the internal magnet (it sits directly beneath the transmitting coil). From there, the sound is distributed to the electrode array. By definition, an electrode is a conductor which allows electricity to transfer across items that are nonmetallic (i.e. skin). The electrode array is a collection of tiny electrodes (current cochlear implants can have up to 24), each of which stimulates an area of the auditory nerve fiber inside the cochlea. Finally, the nerve notifies the brain that sound occurred. The more active electrodes that stimulate the nerve, the better the sound quality for the patient.

As technology advances, changes occur with cochlear implants. They are becoming much easier to use and are significantly more cosmetically appealing that they were ten years ago. The third and final post about cochlear implants will be about the latest design/features of cochlear implants--stay tuned!

Sunday, March 20, 2011

Cochlear Implants: Part 1

In the profession of Speech Pathology, one type of service provided is aural rehabilitation. Aural rehabilitation refers to helping people with hearing losses adjust to their loss and learn how to communicate using the resources available to them, whether that be using manual communication (sign language), using a hearing aid or cochlear implant, or using alternative augmentative communication devices, as were discussed in my last post.

The gadget that I will focus on now, is the cochlear implant. A cochlear implant is an electronic device that provides direct stimulation to the auditory nerve, which is responsible for sound perception. This is helpful to people who have hearing loss due to structural abnormalities, but does not help people whose hearing loss is due to deficits with the brain receiving the message. The device is implanted into the cochlea, which is a structure of the inner ear and is depicted here.

A cochlear implant has two basic components: the external component and the internal component. The external component (pictured here) consists of a microphone, a speech processor, and a transmitter. The internal component consists of a receiver, a stimulator, and the electrode array.

Cochlear implants are highly complex devices. Now that you have been introduced to the device itself, stay tuned to my next post, which will focus on how the device works.