Forward masking patterns by low and high-rate stimulation in cochlear implant users: Differences in masking effectiveness and spread of neural excitation

Effect of pulse phase duration on forward masking and spread of excitation in cochlear implant listeners

“…These results echo the findings from Zhou et al [19], who showed that a high-rate pulse train (1000 pps) produced more masking than an equally loud low-rate pulse train (250 pps). This could be due to an accommodation effect, where sub-threshold pulses, which do not evoke action potentials in the neuron, suppress neuron responses for the subsequent pulse.…”

“…Because each neuron would have to be driven harder to achieve sufficient spike activity, they may be more likely to adapt. This seems unlikely, as Zhou et al [19] showed that low-rate stimulation, which produced narrower excitation than equally loud high-rate stimulation, also produced less forward masking.…”

“…Much research effort has been made towards developing methods to reduce SOE and improve the place specificity of the spectral information. Such efforts include increasing the space between activated electrodes by removing channels [16][17][18], lowering the stimulation rate [19], and "current focusing" to spatially restrict current spread [20][21][22][23][24][25]. Current focusing via multipolar stimulation has shown only marginal improvements in SOE, partly due to the higher current levels needed to achieve sufficient loudness.…”

Relationship between electrode position and temporal modulation sensitivity in cochlear implant users: Are close electrodes always better?

“…A recent study from our laboratory also demonstrated that in monopolar stimulation mode, MDTs were better on stimulation sites measured with sharper spatial tuning curves [ 18 ]. Since low-rate stimulation produces narrower excitation patterns than high-rate stimulation [ 19 ], better modulation detection using a lower carrier rate may also be explained by a narrower stimulation pattern.…”