Saturday, August 27, 2011

Auditory Brainstem Response (ABR) Hearing Screen

  • The normal auditory system generates small electrical currents when excited. These electrical responses are the measured response during ABR tests.
  • To record an ABR, small surface electrodes are attached to the head at several places.  An earphone is place in the ear, brief sounds are played, and the electrical signals across the electrodes are recorded.
  • These electrical signals, which include the ABR, are amplified and then fed to a computer, where they are averaged. Signal averaging is used to reduce the recorded level of other ongoing brain activity and to resolve the small electrical responses generated by the auditory system.
  • If hearing is normal, these electrophysiological responses should be observed for low level stimuli.
  • If hearing loss exists, the threshold of these responses will be elevated.
  • ABRs are less dependent on the status of the middle ear, compared to OAE tests, because the response is recorded across surface electrodes and does not have to travel back out through the middle and external ear.

No comments:

Post a Comment