Cortical Evoked Responses (CERA)


This is a test that uses sound stimulation responses to objectively assess your hearing thresholds. Basic audiometry tests, such as pure tone and speech audiometry, are subjective and rely on the subject to voluntarily indicate when a sound has been heard. Objective tests use a computer to measure the electrical activity in the auditory cortex of the brain and central hearing pathways and do not therefore require a patient response. It is performed when there is any doubt over the validity of pure tone audiometry results, particularly in medico-legal assessment, when subjects may attempt to exaggerate the amount of injury induced hearing impairment for financial gain.


After cleaning the skin thoroughly to remove surface oils, electrodes will be placed on your forehead and behind your ears and connected to a computer to measure your electrical brain activity (EEG). You will be required to sit in a dark room with your eyes closed and wearing headphones. You will hear some loud repetitive tone bursts but you are not required to respond to them as all measurements are taken automatically by a computer which records the electrical activity in the hearing pathways in the brain. You will, however, need to stay alert while the audiologist conducts the test, which may take up to 60 minutes.