Neurelec-MXM, the company, the products
the Digisonic® SP cochlear implant system


Vincent JOURDES

NEURELEC-MXM, 2720 Chemin de Saint Bernard 
06224 Vallauris Cedex – France
Laboratoire I3S, UNSA/CNRS UPRES-A 6070 Sophia Antipolis - France



Since 1977, MXM has developed industrial expertise recognized throughout the world in the life science sector.

In the early 1970’s French scientists and clinicians designed and developed an implantable hearing aid and in 1986, MXM launched the Digisonic® programme. This was to lead to the provision of the first multi-channel cochlear implant which was entirely digital, re-programmable and which transmitted the whole sound spectrum.

Founded in 2006, Neurelec is a member of the MXM group of companies. Based in Sophia Antipolis Science Park in Côte d’Azur, Neurelec is mainly present in Europe , north Africa and Middle East.

The company is totally committed to the research, development, manufacturing and commercialization of cochlear implants, auditory implants and other implantable neuro-stimulation devices.

The current cochlear implant systems, the Digisonic® SP and Digisonic® SP'K, allowed complex signal processing algorithm and efficient stimulation strategies to be implemented.

The signal processing strategy is based on weighted overlap filter bank with a 128 points FFT, an input dynamic range from 30  to 100 dB-SPL and a variable and multi-slope compression function to optimize this dynamic.
A calibration of the microphone in a semi-anechoic room is processed to provide a flat response in dB-HL close the behavior of a normal ear. The system is composed of 2 microphones used for  space selectivity.

Several stimulations strategies are used:

–	The Main peak interleaved sampling strategy (MPIS) with stimulation frequencies ranging from 250 to 1000 Hz.
–	The Fundamental Detection Strategy (FDS): the stimulation frequency is  proportional to fundamental  laryngeal frequency detected in real time.      

For both strategies, stimulation is monopolar or common ground, biphasic through capacitive coupling, and sequential. The 64 computed FFT-energy values are grouped into 20 adjustable frequency bands corresponding to the 20 active electrodes. 

Some devices, adapted to specific etiologies has been  also developed: 
–	The Digisonic® SP ABI (Auditory Brainstem Implant) which can correct auditory problems after surgery for a bilateral acoustic neuroma.
–	The Digisonic® SP Multi-Array implant which is a special version of the cochlear implant used in cases where the cochlea has become ossified. 
–	The Digisonic®SP Binaural implant which is an innovative solution to recreate binaural hearing in adults.


  

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