PSY 1101 Study Guide - Midterm Guide: Sensorineural Hearing Loss, Cochlear Implant, Hearing Aid
16 Aug 2016
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MIDTERM 2
Hearing / Audition:
Audition: the sense or act of hearing
Stimulus Input: Sound Waves
3 characteristics to a sound wave
oFrequency: the number of complete wavelengths that pass a point in a
given time (ex. Per second)
Measured in Hertz
Translates into the psychological experience of pitch
Pitch: a tone's experienced highness or lowness; depends on
frequency.
High frequency = high pitch
Low frequency = low pitch
Or the length of the wave; distance between two peaks … long
waves = low frequency = low pitch
oAmplitude: height of the wave
Measured in dB
Zero dB = absolute threshold for hearing
Every 10 dB = 10 x increase in sound intensity
Translates into the psychological experience of loudness /
intensity
oComplexity: How many frequencies or amplitudes
Translates into the psychological experience of timbre
Timbre: makes voice unique
The Ear:
Outer Ear: visible part of ear
ochannels the waves through the auditory canal to the eardrum (a tight
membrane, causing it to vibrate)
Middle Ear: the chamber between the eardrum and cochlea containing three
tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the
eardrum on the cochlea's oval window.
oPiston made of the hammer, anvil & stirrup pick up the vibrations and
transmit them to the cochlea.
Inner ear: the innermost part of the ear, containing the cochlea, semicircular
canals, and vestibular sacs
oCochlea: a coiled, bony, fluid-filled tube in the inner ear
Sound waves travelling through the cochlear fluid trigger nerve
impulses
oThe incoming vibrations cause the cochlea's membrane (oval window) to
vibrate, jostling the fluid that fills the tube.
Damage to the cochlea's hair cell receptors (or associated nerves)
can cause sensorineural hearing loss or conduction hearing loss
sensorineural hearing loss: nerve deafness
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Conduction hearing loss: hearing caused by damage to the
mechanical system that conducts sound waves to the cochlea
Less common
Caused by disease, or biological changes (heredity,
aging, exposure to loud music)
Too loud = 100 dB, can't talk over the noise, hurts
your ear
Cochlear implant: a device for converting sounds
into electrical signals and stimulating the auditory nerve
through electrodes threaded into the cochlea
oThis motion causes ripples in the basilar membrane bending the hair cells
(cilia) lining its surface.
Cilia: sensory receptors in the ear
Louder → more of the hair cells sway
oHair cell movement triggers impulses in nearby nerve cells. Axons of
those cells converge to form the auditory nerve which sends neural messages
(via the thalamus) to the auditory cortex in the brain's temporal lobe.
oThe pinna catch sound waves → auditory canal → eardrum vibrates →
ossicles vibrate → oval window vibrates → pressure waves in the cochlear fluid
→ basilar membrane vibrates → cilia sways in the basilar membrane →
auditory nerve → BRAIN
Perceiving Loudness:
Soft, pure tone activates only a few hair cells attuned to its frequency
In louder sounds, neighboring hair cells also respond
oThe brain interprets loudness from the number of hair cells activated
oIf a hair cell loses sensitivity to soft sounds, it can still be activated by
loud sounds
Compressed sound: harder to hear sounds are amplified more
than loud sounds
Perceiving Pitch
Place Theory: in hearing, the theory that links the pitch we hear with the place
where the cochlea's membrane is stimulated
oHerman von Helmholtz
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oSound waves of different frequency will activate different areas of the
basilar membrane
High frequency → beginning of membrane
Low frequency → activates the end of the membrane
Frequency Theory: in hearing, the theory that the rate of nerve impulses
travelling up the auditory nerve matches the frequency of a tone, thus enabling us
to sense its pitch.
oFrequency of wavelength influences the rate of firing of hair cells
High frequency → high firing
Low frequency → low firing
o1 Hz = 1 action potential
oBUT hair cells can only fire 1000 action potentials/s yet humans can hear
sounds up to 20 000 Hz.
Volley Principle: neural cells can alternate firing in rapid
succession to achieve a combined frequency above 1000 waves per
second.
Place theory best describes how we sense high pitches, frequency
theory best describes how we sense low pitches and the combination of
place and frequency theory describes intermediate pitches.
Locating Sounds
oThe brain - monitors both ears simulktaneously and looks for
Time of arrival
loudness
o2 ears better than one because
One ear can receive a more intense sound
One ear can receive sound earlier than the other
Hearing Loss and Deaf Culture
oSensorineural hearing loss
Damage to any structure of the ear
Cochlear implant : solution to hearing loss
oConduction hearing loss
Damage to structure involved with transportation and
amplification of sound wave
Digital hearing aid
Compressed sound: amplify soft sounds and leave loud
sounds.
The Other Senses
Touch
oCutaneous senses: multiple senses within the skin
oReceptors: Different combinations activate different stimulations
Itch
Pain
Repeated stroking of a pain spot causes itching sensation
Pressure
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PSY 1101 Full Course Notes
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Document Summary
Audition: the sense or act of hearing. Frequency: the number of complete wavelengths that pass a point in a given time (ex. Pitch: a tone"s experienced highness or lowness; depends on frequency. Or the length of the wave; distance between two peaks long o o waves = low frequency = low pitch. Every 10 db = 10 x increase in sound intensity. Translates into the psychological experience of loudness / intensity. Outer ear: visible part of ear o channels the waves through the auditory canal to the eardrum (a tight membrane, causing it to vibrate) Middle ear: the chamber between the eardrum and cochlea containing three tiny bones (hammer, anvil, and stirrup) that concentrate the vibrations of the eardrum on the cochlea"s oval window. o. Piston made of the hammer, anvil & stirrup pick up the vibrations and transmit them to the cochlea.
