الفهرس 
Anatomy
Anatomy of the inner earOnly 14 pages are availabe for public view
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Abstract
ERA is the name given to the recording of bioelectric changes evoked by sound stimuli in the vicinity of the cochlea, auditory nerve, brain stem and cerebral cortex. Different terms are applied for the different responses arising from various parts of auditory pathway and different kinds and positioning of electrodes are nedeed. for recording, using the same basic principle. The responses evoked by the repeated, stimuli are treated in a way that the responses obtained at electrode sites are recorded, amplified, filtered, summated and averaged, then stored in a computer memory. According to the placement of the electrodes, the ERA is either Electrocochlography (BCochG.) or vertex potentials, the main types of the later are brain stem evoked respons (BERA) and cortical evoked response. ECochG.records the electrical respons of the cochlea and cochlear nerve during the first 5 m. sec. from the start of auditory stimuli, it is either recorded by transtympanic or by extratympanic route, the transtympanic is easier.