Question
What is the difference between a CE-Chirp stimuli and a click stimuli for ABRs?
Answer
The ABR is an onset response that is the result of simultaneous neural firings in the cochlea. The more synchronous the firings, the more robust the ABR. Since the click is a broadband stimulus, it activates the entire basilar membrane (which is good) but because of the organization of the cochlea and the traveling wave, it activates each frequency region of the cochlea at different times (which is not good). The CE-Chirp takes this into consideration and is engineered to adjust the timing of the frequencies presented to the ear. The low frequencies of the stimulus are presented before the high frequencies to offset, or correct for, the traveling wave delay. This adjustment results in more synchronous firings because all the frequency regions of the cochlea are stimulated at the same time. The result is an ABR that is 1.5 - 2 times larger than the click ABR.
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