Sound signal processing.
In the CHORIMAC-12, the French device, the whole speech information despite its redundancy is transmitted to the few cochlear nerve fibers that are still present. Only loud speech intensities between 40 db and 100 db are introduced in a filter battery which gives out the frequency information in 12 channels including the 100-6000 Hz. This 60 db intensity scale is transmitted in a compression rate of about 6 db. The time sampling is 3 msec. A 12 electrode bearer or 12 separate electrodes (in case of ossified cochlea) transmit the electrical information. The electrical stimulus is a square wave: its frequency is equal or inferior to 300 Hz; its voltage may vary between 2.5 and 6.5 volts; its duration may vary between 0 and 200 mu sec. The performances of the system is demonstrated by means of a system of computerized psychophysic tests and speech intelligibility tests.
D003054:Cochlear Implants; D003056:Cochlear Nerve / Q000503:physiopathology; D003638:Deafness / Q000503:physiopathology / Q000534:rehabilitation* / Q000601:surgery; D004567:Electrodes, Implanted; D006801:Humans; D009412:Nerve Fibers / Q000502:physiology; D010700:Phonetics; D013061:Speech Acoustics; D013067:Speech Perception