AUDITORY SYSTEM Hearing is one of the major sense which is important for communication. Organ of hearing have three parts which is Outer ear, Middle ear and Inner ear. Outer ear: Outer ear is divided into two parts first one is Pinna which is protrudes from one side of the skull made of cartilage made of skin. Pinna is also known as Auricle. Pinna is helpful in localising environmental sounds. External Auditory Canal: EAC is also known as ear canal which is about 4 cm long. The outer portion of EAC is lined with hairy skin containing sweat gland and oily sebaceous gland which together form ear wax.