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Hearing: How do we hear?. Hearing: The Nature of Sound. Module 9: Sensation. Sound. Sound, like light, comes in waves Sound is vibration Features of sound include: Pitch Hertz decibels. Pitch. A sound’s highness or lowness Dependent on the frequency of the sound wave
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Hearing: The Nature of Sound Module 9: Sensation
Sound • Sound, like light, comes in waves • Sound is vibration • Features of sound include: • Pitch • Hertz • decibels
Pitch • A sound’s highness or lowness • Dependent on the frequency of the sound wave • Is measured as hertz (Hz)
Hertz (Hz) • A measure of the number of sound wave peaks per second; measures “frequency” • Determines the pitch of the sound • Human hearing goes from 20 Hz to 20,000 Hz
Decibel (dB) • A measure of the height of the sound wave • Determines the loudness of the sound • Sometimes called amplitude
Pitch • A sound’s highness or lowness in tone • Dependent on the frequency of the sound wave – the more “waves per second” the higher the frequency or pitch • Is measured as hertz (Hz)
Hertz (Hz) • A measure of the number of sound wave peaks per second; measures “frequency” • Determines the pitch of the sound • Human hearing goes from 20 Hz to 20,000 Hz
Decibel (dB) • A measure of the height of the sound wave • Determines the loudness of the sound • Sometimes called amplitude
What are good sounds versus bad • What volume do you think is okay? • Not good, not bad? • Bad?
Hearing: The Structure of the Auditory System Module 9: Sensation
Break It Down • Sound waves are collectedin the outer ear, amplifiedin the middle ear, and transduced, in the inner ear.
PINNA The visible part of the outer ear. • It collects sound and directs it into the outer ear canal.
Auditory Canal • The opening through which sound waves travel as they move into the ear for processing • Ends at the eardrum
Eardrum • Also called the tympanicmembrane. A thin membrane that vibrates when sound waves reach it. • it transfers sound vibration from the air to the tiny bones of the middle ear • Can be damaged by objects in the ear or exceptionally loud noises
Bones of the middle ear - Ossicles • Three tiny bones that transfer sound waves from the eardrum to the cochlea • Hammer, anvil and stirrup • Fun fact: the stirrup is the smallest bone in the human body – only .25 cm
Oval Window • The point on the surface of the cochlea which receives the sound vibration from the bones of the middle ear (ossicles) • As the oval window vibrates, the fluid in the cochlea vibrates.
Cochlea • A hearing organ where sound waves are changed into neural impulses (transduction) • The major organ of hearing • Filled with fluid; a snail shaped body tube
Hair Cells • The receptor cells for hearing in the cochlea that change sound vibrations into neural impulses • Transduction!
Auditory Nerve • The nerve that carries sound information from the ears to the temporal lobes of the brain
Divisions of the Ear • Ear’s structure can be divided into: • The outer ear • The middle ear • The inner ear
Hearing • Sound comes into the ear • Goes through the ear canal to the eardrum • Ear drum changes sound into vibrations • Vibrations go through middle ear to the inner ear –
Hearing • Where vibrations are changed into neural impulses so that the brain can read / interpret the sound – • What are the receptors cells for hearing?
Problems with hearing • Conduction deafness* (middle ear damage) • Nerve deafness (hair cell or auditory nerve damage)
Hearing: Sound Localization Module 9: Sensation
Localization of Sound • Locating where sound is originating from • Done through two cues: • Which ear hears the sound first? • Which ear hears the louder sound?
YOU Break It Down This Time. • Sound waves are ______in the outer ear, _______in the middle ear, and ________, in the inner ear.
Another sense in your ears? • Is there another sense in your ear? • Time to do an experiment – let’s find out… out to the hallway we go!!!!
Vestibular Sense • The system for sensing body orientation and balance • Relies on fluid in the semicircular canals of the inner ear • Spinning in circles disrupts the fluid.