Relative Importance of Rate and Place: Experiments Using Pitch Scaling Techniques with Cochlear Implant Recipients

Abstract

Pitch scaling was used to determine the dependence of perceived pitch on rate and place of stimulation in postlingually deafened adult subjects using cochlear implants. For stimulation rates below about 500 pulses per second (pps), perceived pitch is a strong function of both rate and place. In this range, perceived pitch increases logarithmically with stimulation rate, but decreases with distance from the round window. A 2-mm displacement into the cochlea has an effect similar to that of halving the stimulation rate. Place resolution in this context is comparable with the interelectrode spacing (0.75 mm). At rates approaching 1,000 pps, rate has little effect on perceived pitch. An average of bipolar quality judgments showed that periodic pulsatile stimulation is least pleasant when low frequencies are applied to the region closest to the window.