Unit 4(D):
Hearing
Mr. McCormick
A.P. Psychology
Do-Now
(Discussion)
Why does one’s voice sound so different
when it is recorded and played back?
Hearing
 Audition:
 The sense or act of hearing
The Stimulus Input: Sound Waves
 Sound waves are compressing and
expanding air molecules
 Frequency:
 The number of complete wavelengths that
pass a point in a given time (for example, per
second)
 Pitch:
 A tone’s experienced highness or lowness
The Stimulus Input: Sound Waves
 Amplitude:
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The height of a sound wave
Measures the energy/intensity of the wave
Loudness
Measured in decibels
Typical Decibel Levels
Loudness of Sound
120dB
70dB
The Ear
The Cochlea
Perceiving Pitch
 Place Theory:
 Links the pitch we hear with the place where the cochlea’s
membrane is stimulated
 Different frequencies vibrate in different places of the cochlea
 Problem: low-pitched sounds not localized
 Frequency Theory:
 The rate of nerve impulses traveling up the auditory nerve
matches the frequency of a tone, enabling us to sense its pitch
 The entire cochlea is believed to vibrate at a particular frequency
 Problem: high-pitched sounds (1,000 waves/second) travel
faster than neurons
Locating Sounds
Because we have two ears, sounds that reach one ear
faster than the other ear cause us to localize the sound.
Locating Sounds
 Why is it difficult to locate a sound when it
occurs directly ahead, behind, overhead,
or beneath us?
 It is easier to locate a sound when it
comes from either side of us; for this
reason, to pinpoint a sound, we often need
to cock our head, allowing each ear to
receive a slightly different message.
Hearing Loss and Deaf Culture
 Conduction Hearing Loss:
 Caused by damage to the mechanical system that
conducts sound waves to the cochlea
 E.g. punctured eardrum
 Sensorineural Hearing Loss:
 Caused by damage to the cochlea’s receptor cells or
to the auditory nerves
 “Nerve Deafness”
 Biological changes associated with heredity, aging,
and prolonged exposure to ear-splitting noise or
music
Hearing Loss and Deaf Culture
 Cochlear Implant:
 A device for converting sounds into electrical
signals and stimulating the auditory nerve
through electrodes threaded into the cochlea
Hearing Loss and Deaf Culture
 What are the benefits and limitations of
using sign language exclusively in a
hearing world?
 What should the hearing world’s
response be to the use of sign language?
Review
 What is determined by the frequency of a
sound? The amplitude?
 Discuss the path in which sound travels
between entering the ear and reaching the
brain.
 How do we locate sounds?
 What is the difference between Conduction and
Sensorineural Hearing Loss?
Homework
 Unit 4 FRQ
 Unit 4 Quiz: “Sensation and Perception”
 Unit 4 Test: “Sensation and Perception”
 Chapter 5 Outline: “States of
Consciousness”