Sound How You Hear Sound

What is Sound? Sound is Longitudinal waves that travel through a medium & can be heard when they reach a person’s or animal’s ear –Also called sound waves Remember: –Decibels measures amplitude (volume/loudness of sound) –Hertz measures frequency (pitch of sound)

How Does It Work??? You are sound asleep. Suddenly, your alarm goes off and you jump awake. How does your brain receive this information?

Function The ears gather sound waves & send information about sound to your brain Three main sections all with different functions –Outer Ear –Middle Ear –Inner Ear

Outer Ear The part of the ear you see It acts like a funnel, collecting sound waves & directing them into the narrow region called ear canal Only a few cm long and ends at the eardrum Eardrum – small, tightly stretched, drum-like membrane Sound waves make the eardrum vibrate

Middle Ear Located behind the eardrum HAS 3 smallest bones in the body –H ammer, A nvil, S tirrup The hammer is attached to the eardrum When the eardrum vibrates, hammer does too Transmits vibrations first to anvil then stirrup

Inner Ear There is a membrane that separates the middle ear from inner ear When the stirrup vibrates against the membrane, vibrations pass into the cochlea cochlea is a fluid filled cavity shaped like a snail shell Contains more than 10,000 tiny hair cells

Inner Ear Cont. –Hair like projections float in a fluid in the cochlea –When vibrations move through the fluid, hair cells move, causing messages to be sent to the brain through the auditory nerve The brain then processes messages and tells you what you heard

- How You Hear Sound

Hearing Loss If hearing is damaged, it may cause a difficult time hearing soft sounds or high-pitched sounds Can be caused by –Injury –Infection –Exposure to loud sounds –Aging

Causes of Hearing Loss Can occur if the eardrum is damaged or punctured Infections can damage the inner ear Excessive loud music can damage hair cells so signals can no longer be sent to the brain With age, some hair cells die in the cochlea and are never replaced