How They Work?
A cochlear implant System Consists of a Sound Processor and the actual Cochlear Implant.
The Sound Processor
The sound processor consists of the front end signal processing with the microphone(s), the digital signal processor and the headset. The sound processor typically is worn like a hearing aid, behind the ear, but off the ear versions and other wearing options are available too.
Front end signal processing is where the sound processor processes all incoming sounds, very much like a hearing aid. However different from a hearing aid the sound processor encodes all sounds to be converted by the implant into electrical impulses, which stimulate the hearing nerve directly. This is also where background noises are suppressed or multi-microphone technology reduces sounds from certain directions.
The headset is the part, which transmits the signals from the sound processor to the implant. It connects via a cable to the sound processor and is held in place over the Implant via a magnet. Depending on the thickness of the skin, different strength of magnets can be used to prevent the headset from falling off easily. Special headset with a built-in microphone is also available. Hydro-phonic microphones are available in headset to be used for swimming and to hear in and under the water. Headset cables can come in a variety of different length to accommodate different wearing options.
The implant is implanted under the skin in a shallow bone bed above and behind the ear. Main components of the implant are the reception coil, the magnet, the digital processing unit and the electrode array with the individual stimulation electrodes. Only the Advanced Bionics Implant is built to resists impacts of up to 6 joules.
The antenna receives signals from the sound processor via the transmitting headset.
The internal magnet connects through the skin with the magnet in the headset and holds the headset in place. In case a high power MRI is needed at any time in the future, the magnet can be removed by a simple surgical procedure.
The digital processing unit which converts received signals into electrical impulses is housed in a small titanium casing to protect it from impacts. The electrode array is the only part which is actually inserted into the cochlear - the hearing nerve will be stimulated from electrical impulses emitted from tiny electrodes on the tip of the electrode array.
Modern Sound processors can have up to 5 different microphone options.
On the top of the sound processor, two microphones which are slightly spaced apart have the ability to automatically or based on patient selection to filter out unwanted signals from certain directions. This functionality is proven to greatly improve speech intelligibility in noisy environments.
Future developments will enable sound processors from both ears to communicate with each other and use microphones receptions from both sides to create beam forming ability to further enhance ability to hear better in noise.
T-Mic is a microphone configuration where the microphone is located inside the ear to pick up signals at the entrance of the ear canal. This is the most natural location to pick up acoustical signals and provides benefits of hearing in noise and overall better speech intelligibility. Additionally, it enables patients to use telephones or headsets normally.
The microphone can also be integrated into the headset, allowing the sound processor to be worn off the ear / anywhere on the body. This is especially useful for smaller children or during physical activities.
Aqua mic is a version of headset microphone which is equipped with an aqua-phonic microphone. This allows the patient to hear in, under and around the water without any compromises on activities duration or sound quality.
Sound Coding Strategies
A sound coding strategy is the software algorithm which processes the income signal in a way for it to be represented as electrical stimuli. There are various different sound coding strategies used today. Different patients respond or prefer different strategies, thus which sound coding strategy is the best for a certain patient can only be determined by actual patient using it. There are no ways to predetermine it before surgery. The more sound coding strategies an implant is able to work with, the more choices the patient has later to find the most suitable one.
Implant Array Configurations
All Advanced Bionics Implant Systems are available with a choice of 3 different implant arrays.
Your surgeon might choose the implant array based on your child's specific needs or if residual hearing preservation is a priority.
1J – also called straight implant array- for easiest surgical insertion into the cochlear.
Helix – this is the traditional curved array to conform to the cochlear shape.
Mid Scala – Advanced Bionics latest implant array with proven least impact on the cochlear structures, preserving residual hearing.
Swimming with a CI with Aqua-mic
Only Advanced Bionics offers a hydrophonic microphone, the Aqua-mic. The Aqua-mic is not just water resistant; you can actual hear under water with it. All this without any additional protection or accessories; just put it on, jump into the water and let the fun begin.