(Makeup for missed discussion on Sept 29, sorry for the super delay!)
Our senses help us to have knowledge about the world and one of those senses is hearing. As we all know, sound waves are the determents for the sense of hearing. When the sound is examined, three distinct features come into prominence, which are loudness, timbre and pitch. All these features depend on frequency, and complexity.
To describe the form of the ear, the outer ear, the middle ear, and the inner ear must be presented. The pinna, the eardrum, ossicles, oval window, cochlea, and cilia are associated to the form of the ear since they are the essentials.
I think that pinna is the one that seems less important but in essence, its role is massive. Without pinna, we wouldn't be able to hear since it is what catches the sound waves and help other materials of ear to sense the sound.