Outer Ear
The pinna, the auditory canal and the tympanic membrane ( ear drum)make up the outer ear The pinna collects the sound and its structure as well as the positioning of the two ears enables the hearer to determine the direction of the sound The auditory canal channels sound waves towards the tympanic membrane The tympanic membrane vibrates in response to changes in air pressure Its maximum amplitude is of the order of 10 m ( less than the diameter of a hydrogen atom)