BAER Testing

BAER stands for Brainstem Auditory Evoked Response, and this measure can be used to assess the function and performance of the hearing process, even in subjects that are not conscious of the test. As a sound is sensed by the ear, the neurological pathway forwards that sensation, ultimately to the brain. This sensing process is visible in the subject's EEG (Electro-encephalagraph -- brain waves), although the waveforms involved are very small. If the audio stimulus is carefully controlled, and the resulting EEG signal is repeatedly recorded, and the waveforms carefully super-imposed one on top of another, a clearly visible response is observed. This is the BAER signal.

Genetic deafness is a common problem among some domestic pet animal breeds. Identifying a hearing impaired animal before it can breed and pass on the condition is an important step in controlling the overall quality of the pet population of these breeds. A simple Baer test performed on both ears, can quickly make this determination.

To actually measure the BAER, an audio stimulus (typically a brief click or short frequency burst of some sort) is presented to the Ear under test. EEG electrodes placed on the head are connected to a very high gain bioamplifier. The resulting EEG signal for a very brief period following the click contains the BAER response. An individual BAER signal has a VERY low amplitude, and so a large number of BAER data collection passes must be summed together to get a readable BAER tracing. Note that this process requires extremely close coupling between the audio Click presentation and the recording of the EEG / BAER response.

The UFI BAERCOM is a Veterinary BAER hearing tester. This portable, 9V battery powered unit incorporates all required BAER circuitry into a compact enclosure, which provides BAER tracing recording and PC computer connectivity as well.

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