Chapter 13: Sound and Music

Human Ear Label: -External Auditory Canal (label it “ear canal”) -Tympanic Membrane (label it “eardrum”) -Malleus (label it “inner ear bones”) -Cochlea You do not need to label anything else!

How do we hear? We get our sense of hearing from the cochlea, a tiny fluid-filled organ in your inner ear Inner ear has two important functions Provide our sense of hearing Provide our sense of balance

How do we hear? Eardrum vibrates in response to sound waves The 3 delicate bones of the inner ear transmit vibrations to the cochlea Fluid in the cochlea vibrates, sending waves that travel up the spiraled shape Nerves near the beginning of the spiral response to longer wavelength (low frequency sounds) Nerves at the end of the spiral respond to shorter wavelength (high frequency sounds)

Range of Hearing Human hearing: 20Hz – 20,000Hz Animals can hear higher frequencies because they have more sensitive structures in their inner ear People lose their range of frequencies as they age Mosquito ringtone Tiny hairs shake when the fluid in the cochlea is vibrated Listening to loud sounds can cause the hairs to break, and you will lose your hearing at a specific frequency

Ultrasound Ultrasound has a frequency MUCH higher than humans can hear (100,000Hz) These waves can pass through the human body easily Medical ultrasounds use refraction and reflection to create images Video