Evaluation of an artifact reduction strategy for electrically evoked auditory steady-state responses: Simulations and measurements

Publication date: 15 February 2018
Source:Journal of Neuroscience Methods, Volume 296
Author(s): Andreas Bahmer, Sabrina Pieper, Uwe Baumann
BackgroundElectrically evoked steady-state response (EASSR) recording is a measure of neuronal response strength after continuous electrical stimulation of the auditory system. In order to suppress the large electrical artifact generated by intracochlear electrical stimulation, a sophisticated artifact reduction processing strategy ("Hofmann procedure") has been proposed (Hofmann and Wouters, 2010). So far, EASSR recordings with artifact reduction procedures were reported only in cochlear implant (CI) users implanted with Cochlear devices (Macquarie, Australia).New methodHere, we demonstrate the application of the Hofmann procedure in CI users implanted with MED-EL (Innsbruck, Austria) devices. To demonstrate potential limitations of the procedure, we calculated discrete time Fourier transformations (DTFT) of various pulse patterns which may be used for EASSR.ResultsEASSR recordings were obtained in three subjects and processed with the Hofmann procedure. Neural response amplitude growth functions and phase for modulated and unmodulated pulse trains at various stimulation rates could be assessed. Simulations of three different interpolation methods aimed to suppress the electrical artifact show that the interpolation of a sinusoidal signal in a temporal window between 0 and 1 ms has demonstrated negligible impact on the spectral amplitude of the signal with a superior performance of a spline interpolation.Comparison with existing methodThe Hofmann procedure, initially developed for recording EASSRs with CIs from the manufacturer Cochlear, was validated for MED-EL devices.ConclusionIt is feasible to record EASSRs with the described measurement setup and CIs from the manufacturer MED-EL.



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