Dichotic LIstening: 

     Is a psychological test used on the auditory system to explore selective attention. This test branches out into cognitive psychology and neuroscience. There are variations of a standard dichotic listening test to account for other variables such as emotion. In the standard test, headphones are used to send two different stimuli (usually speech) into different ears. The participants are told to pay attention to either one or both of the stimuli and are later asked about the content of the messages they were either told to listen to or not to. In the realm of neuroscience, dichotic listening tests can be used as a lateralized speech assessment task. This helps neuropsychologists explore speech perception and language asymmetry.

This test is mentioned in the Cocktail Party Effect, check it out!