The tone perception improvement of Putonghua in cochlear implant simulation based on the all phase DFT filter

The current cochlear implant (CI) user is bad on the tone perception.Based on the mechanism of multi- channel cochlear implant,the relative perceptual importance of envelope and fine time structure for tile tone reception is studied by the auditory chimaera experiments,in which the envelope and fine time structure from 16 channel signals are extracted and decomposed by a type of zero (or all) phase DFT filter banks and Hilbert transformation,and then applied to synthesize the auditory chimaera in several manners.The tone perception results by the normal hearing listeners show that the fine time structure is more important to tone perception than the envelope,and the impact of the low channels below 1.2 kHz is more significant than that of the higher channels.We found,on the fixed channels,the fine time structure is correspond to the envelop timing,which is determined by the channel central frequency and phase information,and then effects on the electrode pulse firing time.So it is concluded that between the fixed channels the proper adding pulse firing time control on the low channel electrodes is vital for improving current CI tone perception, meanwhile the phase fidelity of filter banks is remarkable.