Final answer:
The tympanic membrane, also known as the eardrum, separates the external auditory meatus from the middle ear.
Step-by-step explanation:
The membrane that separates the external auditory meatus from the middle ear cavity is the tympanic membrane. Also known as the eardrum, the tympanic membrane is responsible for converting sound waves that travel through the ear canal into mechanical vibrations. These vibrations are then transferred to the ossicles within the middle ear. The ossicles consist of three small bones called malleus, incus, and stapes, which further transmit sound to the inner ear where the cochlea converts them into neural signals.