EAS is a hearing implant solution designed for people with partial deafness. These individuals have residual hearing in the low frequencies but have a profound hearing loss in the high frequencies. For people with partial deafnesss, hearing aids often provide unsatisfactory results in understanding speech or listening to complex sounds such as music. Traditional cochlear implant systems are also not ideal because they do not allow users to benefit from their natural low frequency hearing abilities.

Combined Electric Acoustic Stimulation, or EAS, is the concept of using acoustic amplification and cochlear implant technology together in the same ear. With EAS, the inner ear is provided with acoustic and electric stimuli and is able to process both high and low frequency information simultaneously.

EAS consists of two parts, an external and an internal component.


  • Implant
    The implant consists of a housing, which contains the electronics, and the electrode array as well as the receiving antenna and a magnet that holds the coil in place behind the ear.


  • Audio processor
    The Audio processors features a digital acoustic unit for amplification that enhances a person’s natural low-frequency hearing and is worn behind the ear. For higher frequency sounds, the cochlear implant function automatically takes over. The intelligent integration of both modalities results in a synergistic effect for speech and sound perception offering an optimal solution for individuals with partial deafness.

How does EAS work?


EAS is the combination of two technologies, each responsible for a specific frequency range. Here is how it works:

  • A cochlear implant converts everyday sounds into coded electrical pulses. These pulses stimulate the auditory nerve. The brain interprets these signals as sound.
    1. High frequency sounds are picked up by the microphone of the DUET 2 Audio Processor and converted into a special code.
    2. This code is sent to the coil and is transmitted across the skin.
    3. The implant interprets the code and sends electrical pulses to the electrodes in the cochlea.
    4. The auditory nerve relays this signal to the brain.
  • Acoustic amplification turns up the volume on the sounds that the cochlea is still able to hear. For EAS, only the low frequencies are amplified.
    1. Low frequency sounds are picked up by the microphone and are digitally processed and separated.
    2. Sounds are amplified by the loudspeaker located in the ear hook and relayed via the ear mould to the ear canal.
    3. Sounds reach the undamaged areas of the cochlea responsible for processing low frequency sound.
    4. The auditory nerve relays the signals to the brain.
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