الفهرس 
Functional Anatomy of the CochleaOnly 14 pages are availabe for public view
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Abstract
C
lick-evoked-ABR is the most widely used electrophysiologic procedure for estimating auditory sensitivity in infants and children (Johnson, 2002). At moderate intensity levels, the click stimulus activates a large portion of the cochlea with firing of neural units over an extended frequency range (Don et al., 1979). This yields a highly repeatable response, wave V can be detected at intensity levels within about 10 dB of the average behavioral audiogram in the (1000 to 4000)Hz frequency region in children and adults (Johnson, 2002).
The tone bursts yields better predictions of the peripheral sensitivity than the click-evoked responses, particularly in the case of sloping or unusual audiometric configurations (Sininger & Abdala, 1998). ABR to tone bursts can be recorded at intensity levels within 10 dB of the behavioral thresholds for similar frequency stimuli (Sininger & Abdala, 1998).
Evidence for a significant increase in ABR amplitude, mainly wave V amplitude, in adults when a chirp stimulus is used can be found in the literature (Fobel and Dau, 2004; Elberling et al., 2007). The improved response identifiability achieved through the greater response amplitude seems to be stimulus level-dependent being better at and near threshold compared to the “gold standard” chirp stimulus (Cebulla et al., 2014).Being larger in amplitude, chirp stimulus was superior to the click stimulus in evoking lower ABR thresholds in both control and cases. Absence of waves I and III is an important limitation.
Shorter latencynoticed especially at high stimulation support the hypothesis that the compensation for traveling wave delay implemented in the chirp stimulus shortens the latency and shifts the waves. The structure of the chirp stimulus decisively influences the deflection of the basilar membrane and thus the timing of the stimulation of the basilar membrane hair cells in the inner ear.
Different latency frequency behavior was noted with NB CE-chirp. With NB CE-chirp wave V latency decreased as stimulus frequency decreased. At 500Hz compared to 1000 and 2000 Hz, larger differences between behavioral and NB CE-chirp evoked ABR response.
It can be concluded that chirp-evoked potentials are distinguished from click-evoked potentials by their significantly larger ABR amplitudes. The chirp stimulus is expected to yield more reliable results, and especially shorter measurement times, and ultimately to lead to an improved quality of hearing threshold assessment and hearing screening.