A frequency peak at 3.1 kHz obtained from the spectral analysis of the cochlear implant electrocochleography noise
Fig 1
Schematic illustration comparing induced and evoked FFT methods.
Single-trial electrocochleography signals are depicted in the orange panel, showing three trials in the time domain containing transient synchronous (blue) and asynchronous (red) activity. Blue signals represent evoked responses (such as cochlear microphonics responses observed with auditory stimulation in electrocochleography), while transient red signals exhibit temporal jitter, which can be recorded during spontaneous or stimulus induced conditions. Below the orange panel, the averaged (evoked) trace preserves synchronous activity (blue), while eliminating asynchronous activity (red), and consequently the “evoked” FFT from this time-averaged signal, only captures the frequency peak of the corresponding evoked potential (blue peak). On the other hand, the light-blue panel shows three single trial PSDs directly calculated from single trial electrocochleography signals keeping synchronous (blue) and asynchronous (red) activity. These single trials PSDs are averages to obtain the “induced” FFT, which captures both peaks of activity.