1. Myers PSYCHOLOGY Seventh Edition in Modules
Hearing
James A. McCubbin, Ph.D.
Clemson University
Worth Publishers

2. Audition Audition Amplitude
the sense of hearing
Amplitude
- the measure of the height of a sound wave
Frequency
the number of complete wavelengths that pass a point in a given time
Pitch
a tone’s highness or lowness
depends on frequency

3. The Mechanics of a Sound Wave
Measure of amplitude (height of wave) is directly related to volume.
Frequency (amount of wavelengths in a given time) is directly related to pitch.

4. Measuring Sound Decibels are the measuring unit of sound
Absolute threshold is arbitrarily defined as 0 decibels
Every 10 decibels corresponds to a 10 fold increase in sound
Whisper = 20 decibels
Normal conversation = 60 decibels
Passing Subway train = 100 decibels
Prolonged exposure to sounds above 85 decibels can produce hearing loss

5. The Intensity of Some Common Sounds

6. Audition- The Ear Middle Ear Inner Ear Cochlea
chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window
Inner Ear
innermost part of the ear, containing the cochlea, semicurcular canals, and vestibular sacs
Cochlea
coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses

8. How we transform sound waves into nerve impulses our brain interprets
The outer ear funnels sounds waves to the eardrum
Bones of the middle ear amplify and relay the eardrum’s vibrations through the oval window into the fluid-filled cochlea
Pressure changes in the cochlear fluid cause the basilar membrane to ripple, bending the hair cells on the surface
Hair cell movement triggers impulses at the bases of the nerve cells, whose fibers converge to form the auditory nerve

9. Place Theory Developed by Hermann von Helmholtz
the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated
Georg von Bekesy (1957) cut holes in
the cochleas of guinea pigs and human
cadavers, using a microscope and
observed that it vibrated in response
to sound
High frequency produce large vibrations near
beginning of cochlea’s membrane and low
frequency near the end
Explains how we sense high pitches

10. Frequency Theory
the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense pitch
Differing from place theory, it suggests that the entire cochlear membrane vibrates with every sound: it does not matter what the frequency of the sound is for it to vibrate in a certain area
Explains how we sense low pitches

11. How We Locate Sounds

12. How do we locate sounds
Placement of our two ears allows “three-dimensional sound”
2 ears are better than 1
One receives sounds slightly sooner and more intense than the other
Despite how small the differences are the auditory system can detect them and locate where the sounds are coming from
Sounds that are equidistant from both ears can be difficult to locate

13. Audition Conduction Hearing Loss
hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea
Digital hearing aids can improve hearing by amplifying vibrations for frequencies (usually high) in which one’s hearing is weakest and by compressing sounds (amplifying soft but not loud)

14. Audition Sensorineural Hearing Loss
hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve
also called nerve deafness
Usually results from prolonged exposure to loud noises and biological factors linked with aging
Once destroyed, tissues cannot regenerate in humans. With sharks, birds, and some other animals, hair cells of the inner ear can regenerate
Hearing aids can amplify sounds in order to activate neighboring hair cells

15. Audition Sensorineural Hearing Loss (cont.)
New solution = cochlear implant: an electronic device that translates sounds into electrical signals that, wired to the cochlea’s nerves, conveys some info about the sounds to the brain
Helps children with sensorineural hearing loss to strengthen their oral communication
Can restore hearing and communication to deaf adults who could previously speak and communicate

16. Audition
Older people tend to hear low frequencies well but suffer hearing loss for high frequencies 1
time 10
times
100
1000 32 64
128
256
512
1024
2048
4096
8192
16384
Frequency of tone in waves per second
Low
Pitch
High
Amplitude required for
perception relative to
20-29 year-old group

17. Deaf Culture
Cochlear Implants = major debate b/c deaf culture advocates say they aren’t linguistically disabled
Sign language has its own grammar, syntax, and semantics
Children that only learn sign language have difficulty later on grasping the concepts of grammar in their native spoken language

18. Deaf Culture
People that are starved of certain sensory input often compensate with their other senses
Deaf people’s auditory cortex becomes responsive to touch and visual input
Their reading is not superior but they tend to have better visual skills making them better visually skilled engineers, architects, and mathematicians
Only about 1% of people that experience hearing loss are born deaf

19. Terms Review Audition Frequency theory Frequency Pitch
Middle ear
Inner ear
Cochlea
Place theory
Frequency theory
Conduction hearing loss
Sensorineural hearing loss