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Sound waves and the Ear. Sound. Sound travels in waves. We “hear” vibrations of molecules. Speed of Sound . Depends on what it is traveling through. Air 3 40 m/s Liquids 1400 m/s Solids 5500 m/s Why? The more dense = more particles to pass on energy. Frequency.
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Sound Sound travels in waves. We “hear” vibrations of molecules.
Speed of Sound • Depends on what it is traveling through. • Air 340 m/s • Liquids 1400 m/s • Solids 5500 m/s • Why? • The more dense = more particles to pass on energy
Frequency • Human hearing is between 16Hz-20 000Hz (20 kHz) • Dogs can hear up to 80 000 Hz and bats up to 120 000 Hz • Hearing test • http://www.youtube.com/watch?v=4G60hM1W_mk
The Decibel Scale • A relative scale measuring the intensity or amplitude of noise • Above 100 dB will do damage to the ear. • Above 120 dB – pain and immediate loss of hearing
Pinna or Auricle Auditory canal Outer Ear
Outer Ear • Pinna or Auricle • Only visible part of ear • Shaped like a funnel • *picks up sound vibrations
Outer Ear • Auditory Canal • 2.5 cm long • *carries sound vibrations to ear drum • Lined with fine hairs and glands that secrete wax –> • *preventsforeign particlesfrom entering ear (ex. dust)
Ossicles Pinna or Auricle Tympanic Membrane Eustachian tube Auditory canal Outer Ear
Middle Ear • Tympanic Membrane (eardrum) • Thin flexible membrane • About 1 cm in diameter • *moves with sound vibrations
Middle Ear • Ossicles • 3 small bones • Amplify the sound waves by 20%
Middle Ear • Eustachian Tube • Connects middle ear to pharynx • Equalizes pressure during swallowing
Semi-circular canals Ossicles Pinna or Auricle Cochlea Vestibule Tympanic Membrane Eustachian tube Auditory canal Outer Ear
Inner Ear • Semi-circular canals • Filled with liquid • *BALANCE when moving*
Inner Ear • Vestibule • Links semi-circular canals to the cochlea • Balance when not moving
Inner Ear • Cochlea • Liquid filled • Walls covered with hairs (auditory nerve cells) • Hairs transform vibrations into a nerve impulse
Semi-circular canals Auditory Nerve Ossicles Pinna or Auricle Cochlea Vestibule Tympanic Membrane Eustachian tube Auditory canal Outer Ear
Auditory Nerve • Sends information (nerve impulses) to the brain
Video clips • Intro – parts - http://www.youtube.com/watch?v=ahCbGjasm_E&feature=related • Stomp - http://www.youtube.com/watch?v=KY7_TIktQFs&feature=PlayList&p=FE42A62D04D5C9B7&playnext=1&playnext_from=PL&index=6 • Hearing loss and hair cells - http://www.youtube.com/watch?v=MGj-cdn2M9o&feature=PlayList&p=FE42A62D04D5C9B7&playnext=2&playnext_from=PL&index=7