Answer:
a double dissociation.
Explanation:
Double dissociation is a psychological term used to describe a scenario whereby two mentally concerned processes are independent in function i.e they work specifically for different functions. In double dissociation, damage to one neurological (brain) area affects only one of two functions and have no effect on the other.
This is the case in this question where a neurologist noticed that damage to brain structure A of a patient resulted in a major disruption in speech production, but left hearing ability intact while a damage to structure B in another patient left major hearing impairment, but did not affect speech production. This example portrays what DOUBLE DISSOCIATION explains.
