What is the medical term for the air-filled space behind the eardrum?

The correct answer is the middle ear. The middle ear is the air-filled space located behind the eardrum (tympanic membrane) and plays a crucial role in hearing by transmitting sound vibrations from the eardrum to the inner ear. This space contains the ossicles, which are small bones that amplify and transfer sound waves.

The cochlea is part of the inner ear and is responsible for converting sound vibrations into nerve impulses. The outer ear consists of the part you can see (the pinna) and the ear canal, which leads to the eardrum but does not contain air-filled space. The inner ear houses organs critical for both hearing and balance but does not refer to the area behind the eardrum. Thus, the middle ear is the correct term for the air-filled space behind the eardrum.