JOURNEY THROUGH THE EAR

THE JOURNEY BEGINS

• Noise is collected by the outer ear or the pinna
• Pinna- the largely cartilaginous projecting portion of the external ear
• Catches and guides sounds to the eardrum (tympanic membrane)

SOUND WAVES TRAVEL

• Sound moves through the ear canal to the ear drum
• Eardrum is a membrane in the ear canal between the external ear and the middle ear
• The eardrum is also called the tympanic membrane
• When sound waves hit the eardrum it vibrates
• The eardrum is streched across the entrance of the middle ear, and transmits sounds to the ossicles

THE MIDDLE EAR

• The ossicles are the three bones in the middle ear
• As sound waves vibrate the eardrum.. It moves the nearest ossicle the hammer, which is attached
• The hammer then transmits vibrations via the anvil to the stirrup
• Ultimately to the membrane of the oval window- the opening to the vestibule of the inner ear
• The oval window is simply a connective tissue

INNER EAR

• The cochlea looks like a snail shell
• The mechanical vibrations in the fluid of the cochlea bend the thousands of delicate Hair Cells
• Hair cells change the vibrations into nerve impulses
• The auditory nerve then carries impulses to the brain
• The information eventually reaches the thalamus and then is relayed to the auditory cortex

WAVELENGTH

• Is the distance from the peak of one light or sound wave to the peak of the next

AMPLITUDE

• A waves height

HELMHOLTZ PLACE THEORY

• explains how people determine high pitched sounds
• The theory that links the pitch with the place on the cochleas membrane stimulated

FREQUENCY THEORY

• Explains how people determine low pitched sounds
• The theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone
• Volley principle-neural cells can alternate firing. By rapid sucessuon they can achieve a combined frequency