sentences:  It often takes a noun in the genitive case for a person is being heard, with a noun in the accusative for the thing being heard.More classically, the use of the accusative indicates hearing with understanding.There is indeed a case difference here, with using the genitive "tēs phōnēs" (τῆς φωνῆς), and using the accusative "tēn phōnēn" (τὴν φωνὴν).