Auditory Brainstem Response (ABR) is a test used to evaluate the auditory pathway from the inner ear to the brainstem. It measures the electrical activity generated by the auditory nerve and brainstem in response to sound stimuli. During the test, electrodes are placed on the scalp to record the brain's response to clicking sounds or tone bursts presented through earphones. ABR is commonly used to assess hearing sensitivity, detect hearing loss, and diagnose auditory nerve disorders or brainstem abnormalities. It's especially useful for evaluating hearing in infants and individuals who cannot participate in conventional behavioral hearing tests.