Which part of the ear is known as the outer ear structure?

The pinna is known as the outer ear structure, and it plays a crucial role in capturing sound waves from the environment and directing them into the ear canal. The pinna is the visible part of the ear that is made up of cartilage and skin, and its unique shape helps to amplify and localize sounds coming from different directions.

In contrast, the cochlea is located in the inner ear and is responsible for converting sound vibrations into neural signals, while the incus is one of the three tiny bones in the middle ear that help transmit sound vibrations from the eardrum to the inner ear. The auditory canal, although part of the ear, is classified more as a passageway rather than an external structure. Thus, the pinna's primary role and identity as the outer ear structure distinguish it as the correct choice in this context.