European Homepage Site Map Contact Legal Informations
Search :
Advanced Bionics Europe
  • Welcome
  • |
  • Learning about Cochlear Implants
  • |
  • Choosing your Cochlear Implant
  • |
  • Living with a Cochlear Implant

    • Advanced Bionics Europe

    enfant arrondi
    > Choosing your Cochlear Implant > HiRes® 120 > Active Current Steering

    The current steering technique is similar to the “balance” feature of a Hi-Fi stereo system that shifts the sound image from left to right by simultaneously varying the volume between the two loudspeakers.

    Active current steering is made possible in the HiRes 90K implant because each electrode has its own separate power source - thereby allowing current to be delivered simultaneously to pairs of electrodes. Theoretically, with fine control over the proportion of the current delivered to each electrode of the pair, the locus of stimulation is “steered” between the two electrodes. Thus additional discrete electrode contacts are created.

    The figures illustrate how three different distributions of current on two electrodes create different stimulation patterns :
    acsterring_1.jpg acsterring_2.jpg acsterring_3.jpg
    When current is delivered only to the left electrode the neurons close to it tend to be  stimulated
    When half the current is delivered to each electrode, the locus of the electrical field is midway between the electrodes and the neurons here tend to be stimulated  
    As the proportion of current shifts to the right electrode so does the zone of neurons which tend to be excited  


    The animation illustrate how different distributions of current on two electrodes create different stimulation patterns :
    Move the slider to show  the animation