Simulations of combined acoustic/electric hearing

Normal-hearing listeners were presented signals processed in the manner of a cochlear-implant signal processor in order to estimate the effects of electrode insertion depth in patients with residual low frequency hearing to 500 Hz. Simulations of 19 and 17 mm insertion depths produced better speech understanding than more shallow depths. Simulations that left gaps in the frequency spectrum allowed better understanding than simulations with no gaps and upshifted frequencies. The effects of losing low frequency hearing following an electrode insertion were severe for insertion depths of 15 mm or less. In these cases speech understanding was no better than that achieved with the 500 Hz residual hearing.