Pitch magnitude estimation can predict across-ear pitch comparisons in cochlear-implant users

Abstract

Bilateral cochlear implants provide auditory input in both ears, but sensitivity to interaural time differences (ITDs) varies across individuals. One factor affecting ITD sensitivity is place-of-stimulation mismatch across ears. Currently there is no fast method for estimating mismatch. Since pitch varies depending on place-of-stimulation, our laboratory uses two pitch-matching methods to estimate matched place-of-stimulation across ears: pitch magnitude estimation (PME) and direct pitch comparison (DPC). PME involves rating pitch from 1 (lowest) to 100 (highest) for even numbered electrodes in each ear. DPC involves comparing the pitch of one electrode against six electrodes in the opposite ear, yielding an estimate of place-of-stimulation mismatch at one electrode. DPC predicts interaural electrode pairs with good ITD sensitivity, but is relatively slow because pairs are chosen one at a time. PME is a much faster, global estimate of the relative difference of interaural electrodes, but it is uncertain whether PME can predict the same interaural pairs as DPC. Here, we predict DPC estimates from PME results using regression techniques. Results suggest PME may be an efficient tool for creating clinical maps that yield good binaural sensitivity. [Work supported by NIH-NIDCD R01-DC003083 to RYL, NIH-NIDCD R03-DC015321 to AK, and NIH-NICHD P30-HD03552 to Waisman Center.]