Speech Shadowing:

     Is an experimental technique where immediately after hearing speech, usually through headphones, the participant must repeat what they heard. The test shows reaction times between hearing a word and pronouncing it. Reaction times can be as short as 254 ms or even 150 ms. The technique of speech shadowing can be used in language learning, speech perception, and stuttering. Colin Cherry was the first to use this technique in 1953. Speech shadowing is used in dichotic listening tests to ensure that the participants are attentive to the messages. After speech shadowing has been applied to confirm attentiveness of the listener to one stimuli, secondary stimuli can be added to perform the dichotic listening test.

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