Notes from video 1- introduction to the ear

Diagram of an ear: 

Source: http://www.enchantedlearning.com/subjects/anatomy/ear/earanatomy.GIF

Introducing the different parts of the ear and an introduction as to how sound is introduced into the ear: 

-the oracle (visible part of the ear) collects sound waves and directs them to the auditory canal or ear canal which is lined with cilia and ceruminous glands. The ear wax (which is produced by the ceruminous gland) and the cilia (tiny hairs) trap and prevent foreign matter from getting deep into the ear. 

The thin membrane that separates the outer ear from the middle ear cavity is called the ear drum or the tympanic membrane. 

The sound waves cause the tympanic membrane to vibrate which in turn causes 3 other bones to vibrate:

-(in order): the malleus (hammer), anvil (incus), stapes (sterum). They pick up vibrations form the outer ear and transmit them to the inner ear. 

-The eustachian tube of the inner ear opens into the pharynx (part of the nose that is behind the mouth and nasal cavity-nose space). It allows air pressure to equalize between the ear and the outside air. 

The inner ear consisting membranous structure and bony structures surrounded by fluid. 

Semicircular canals are fluid with fluid, they are bony loops that help us maintain balance. 

The cochlea is a fluid filled snail shaped structure that contains the organ of corti- which is basically the 'true' organ of hearing. 

They change the vibration (actually the hair cells in the organ of corti do this) of nerve impulses into nerve impulses that are picky up by the auditory nerve and then sent to the brain for interpretation.

Introduction to: how are sounds perceived? 

Sound waves are collected by the oracle or outer ear and sent through the auditory canal, the tympanic membrane, ear bones and then to the cochlea. Where the vibrations are changed by the organ of corti to nerve impulse and transmitted by the auditory or cochlea nerve to the temporal lobe (this is a part of the brain) for interpretation. 

Source: Process of Hearing- YouTube.flv

More detailed notes on the organ of corti:

They are the organ that is the space between the two fluid filled tubes, the fluid filled tubes because they are liquid membranous structures they are able to be compressed (how much depends on the amplitude and frequency of the sound waves). Within the organ of corti there are hair cells which then pick up these compressions and depending on it's frequency and amplitude convert those sound waves into nerve impulses which are then sent to the temporal lobe of the brain for interpretation via the auditory or cochlea nerve. Each impulse is not the same as the impulse will be for that specific amplitude and frequency of that particular sound wave.