Evoked response audiometry (ERA) – colloquially called electrical response audiometry testing – refers to the testing of hearing ability based on the recording of nerve activity in the brainstem (cerebral cortex) during hearing. Potentials of the inner ear, the auditory pathway, the brainstem (or brain stem) and the cerebral cortex are measured.
ERA is not a measurement method in its own right, but a collective term for various measurement methods (see “The methods” below).
Indications (areas of application)
- Hearing screening in newborns
- Early detection of intoxications affecting the ear; these occur primarily with cytostatic drugs
- Detection of hearing disorders
- Suspicion of acoustic neuroma – tumor that occurs in the area of the auditory nerve.
The procedures
In the measurement of electrical response audiometry, a periodic stimulus is applied, which under normal conditions leads to a derivable activity in the EEG (electroencephalography).
Note: Electroencephalography (EEG) is a method of medical diagnosis for measuring the summed electrical activity of the brain by recording the voltage fluctuations on the surface of the head. It is used to detect and localize pathological changes in electrical brain activity.ERA (evoked response audiometry; “evoked response” → “evoked response”) includes the following procedures:
| Procedure | Acronym | Measurement |
| Electrocochleography | ECochG | Potentials of the cochlea and auditory nerves. |
| Brainstem electrical response audiometry | ABR | Brainstem potentials |
| Cortical evoked response audiometry | CERA | Potentials of the cerebral cortex |
ABR, in particular, is used nowadays. Here, nerve impulses are derived via electrodes on the head. For more information, see brainstem audiometry.
Checking electrical response audiometry is an informative diagnostic procedure in otolaryngology that can be used to detect or localize hearing disorders at an early stage, because hearing disorders are not always due to the inner ear, but can also have other causes.
