Chapter 4 Sensation and Perception

The Ear Audition = hearing Audition = hearing Sounds = mechanical energy typically caused by vibrating objects Sounds = mechanical energy typically caused by vibrating objects Sound waves – vary in length and frequency Sound waves – vary in length and frequency Strength of sound waves determines their loudness Strength of sound waves determines their loudness The frequency determines their pitch The frequency determines their pitch The longer the waves, the lower the pitch, shorter the waves, higher the pitch The longer the waves, the lower the pitch, shorter the waves, higher the pitch

Parts of the Ear: Three sections of the ear – outer, middle, inner Outer Ear- Ear canal – passage for sound Eardrum- membrane over ear canal: vibrates when sound hits it

Middle Ear- Middle Ear- Hammer,anvil,stirrup- three small bones of the middle ear- helps sound move from eardrum to inner ear Hammer,anvil,stirrup- three small bones of the middle ear- helps sound move from eardrum to inner ear

Inner Ear – transfers sound vibrations into neural impulses Cochlea- snail-like tube which takes incoming vibrations and causes its membrane (oval window) to vibrate the fluid that fills the tube Cochlea- snail-like tube which takes incoming vibrations and causes its membrane (oval window) to vibrate the fluid that fills the tube

Basilar Membrane- inside the cochlea and also attached to the oval window; contains hair cells that move in reaction to sound waves Basilar Membrane- inside the cochlea and also attached to the oval window; contains hair cells that move in reaction to sound waves Eustachian Tube- tube that connects to throat; allows air pressure to equalize between inner and outer ear. Can be blocked during infections, causing pressure Eustachian Tube- tube that connects to throat; allows air pressure to equalize between inner and outer ear. Can be blocked during infections, causing pressure

Pinna- external flap of skin and cartilage Pinna- external flap of skin and cartilage

How sound travels through the ear: sound enters outer ear sound enters outer ear down auditory canal down auditory canal Eardrum Eardrum 3 bones of middle ear 3 bones of middle ear Cochlea – fluid causes basilar membrane to ripple Cochlea – fluid causes basilar membrane to ripple Hair cells in cochlea bend Hair cells in cochlea bend Auditory nerve Auditory nerve Thalamus Thalamus To opposite temporal lobe To opposite temporal lobe

Types of hearing loss 1. Conduction hearing loss – messages to the cochlea are malfunctioned caused by punctured eardrum Middle ear bones can’t vibrate Helped by digital hearing aids by amplifying vibrations

Sensorineural Hearing loss- nerve deafness – caused by damage to the cochlea hair receptors or association areas (inner ear) Sensorineural Hearing loss- nerve deafness – caused by damage to the cochlea hair receptors or association areas (inner ear) Happens because of noise pollution, disease, inheriting, aging Happens because of noise pollution, disease, inheriting, aging Cochlear implant – electronic device that transmits sounds into electrical signals to brain Cochlear implant – electronic device that transmits sounds into electrical signals to brain