Psychology 4.4 THE EARS

sound wave

sound wave

a wave that transmits sound Characteristics:

• amplitude = volume

• wavelength = pitch

• purity = timbre

Outer ear

Pinna, auditory canal/ear canal, tympanic membrane/eardrum

pinna

Collects & amplifies sound

Ear canal (auditory canal)

Entryway for sound waves

Eardrum (tympanic membrane)

Vibrates in response to sound waves

Middle ear

the main cavity of the ear; between the eardrum and the inner ear -tympanic cavity -ossicles (malleus, incus, stapes)

Tympanic cavity

Fluid filled, contains ossicles

Ossicles

Malleus, Incus, Stapes

inner ear

Oval window, Cochlea, Vestibular and Cochlear Nerves

Oval window

The transmission of vibration from the ossicles

cochlea

-the snail-shaped tube where sound vibrations are converted into nerve impulses by the organ of Corti -fluid filled and moves in response to vibration -hair cells line the basilar membrane that acts as receptors

Vestibular & Cochlear Nerves

• forms the vestibulocochlear nerve -transmit sound and vestibular info to the brain

Types of hearing loss

Conductive, Sensorineural, or mixed

conductive hearing loss

Involves outer or middle ear, blockage

sensorineural hearing loss

Involves inner ear, damage to the hair cells

Cochlear implant

-sends signals directly to auditory nerve -for hearing

Place theory

Specific frequencies vibrate particular places of the basilar membrane (front is higher frequency, back is lower)

Frequency theory

-Pitch corresponds to the vibration of the whole basilar membrane (ex. 90 Hz=90 vibrations) -brain detects how fast the basilar membrane is firing and auditory nerve fires at the same rate -limited capacity of 1000x /sec

Auditory cortex

-found in temporal lobe -where sensation becomes perception

Localization of sound

Lateral & Median Localization