Kolloquium WiSe 2019/20

Signal processing in cochlear implants – From surgery to sound perception

Hearing can be restored in deaf people by direct electrical stimulation of the auditory nerve fibers. In cochlear implants, different signal processing techniques are used at various stages of a CI user’s hearing journey. Auditory nerve responses such as the cochlear microphonic are recorded during surgery, and electrically compound action potentials during and after surgery help with fitting. Each requires different techniques in terms of noise reduction and artifact rejection. For electrical hearing, a sound coding strategy transforms the incoming microphone signals to a series of electrical pulses to drive the intra-cochlear electrodes hence representing the frequency and energy of the audio signal. Additionally, techniques such as directional microphones exploit the spatial distribution of sound sources while other speech enhancement schemes remove as much of the interfering background noise as possible without introducing excessive speech distortion. Both approaches substantially reduce background noise, leading to improved speech perception.