Introduction The precise adjustment of the electrical threshold for cochlear implant (CI) users is of fundamental importance for speech perception. Here a psychoacoustic procedure (auto-precT) is presented, which allows the precise determination of the electrical hearing threshold (T-level) for users of CI. The effects of this method on speech perception in the noise of CI users at soft speech levels are examined.
Material and Methods: The test stimuli are generated as audio signals in the auto-precT method and transmitted via a sound card via audio cable to a defined programmed cochlear audio processor (CP910). The two test stimuli have a different presentation level per playback. The CI users are asked after the presentation of the stimuli whether they perceive 0, 1 or 2 test stimuli. The determination of the electrical hearing threshold is adaptive. To use the results directly into the Cochlear Fitting software, the audio signals are calibrated with the CIC4 Decoder Implant Emulator. The auto-precT data of 15 CI users on all electrodes as well as the speech comprehension (OLSA: speech: 50 dB, noise adaptive) are determined with three different programs: (P1) so far used by the CI user, (P2) new determined T values and (P3) same as (P2), but reduced T values by 10 CL.
Results The speech reception threshold in noise improves significantly from (P1) 2.5 dB to (P2) 1.6 dB SNR by the auto-precT method. In (P3), the worst SNR is found with 2.9 dB.
Conclusion Precise adjustment of the electrical hearing threshold with auto-precT in CI provides significantly better speech understanding in noise for low speech levels.
Cochlear Deutschland
Poster-PDF
A-1720.PDF
