Fox squirrel (Sciurus niger): The fox squirrel is the largest tree squirrel in Illinois, weighing one and three-quarters to two pounds with a length of 19 Â½ to 22 inches. The fur is a mix of rusty-yellow with black with an overall reddish cast. The fur on the ears, belly, and edge of the tail is lighter.
Audiologists are able to measure the speed and intensity of these pulses to determine if there is hearing loss or a lesion that is upsetting the flow of the sound information through the brainstem. This measurement is called a brainstem auditory evoked response (BAER).
1 Deafness can be unilateral (affecting one ear) or bilateral (affecting both ears). 2  Partial deafness is difficult to recognize but in some animals, partial hearing loss can be observed by some owners. 3  Unilateral and partial deafness can be tested using a brainstem auditory evoked response (BAER) test.