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Auditory Physiology and Hearing

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Title: Auditory Physiology and Hearing


1
PSY 3520 Sensation and Perception
Auditory Physiology and Hearing
2
Auditory Physiology HearingLecture Outline
  • I. The Stimulus for Hearing
  • A. Pure Tones
  • 1. Amplitude
  • 2. Frequency
  • B. Perceptual Dimensions of Sound
  • C. Complex Sounds and Fourier Analysis
  • II. Structure and Functioning of the Auditory
    System
  • A. Outer Ear
  • 1. Pinnae
  • 2. Auditory Canal (External Auditory Meatus)
  • 3. Tympanic Membrane (Eardrum)
  • B. Middle Ear
  • 1. Ossicles (Malleus/Hammer, Incus/Anvil,
    Stapes/Stirrup)
  • 2. Function of the Ossicles
  • 3. Eustachian Tube
  • C. Inner Ear
  • 1. Cochlear Compartments
  • 2. Organ of Corti
  • 3. Transduction What causes a hair cell to
    bend?

3
Auditory Physiology HearingLecture Outline
  • III. The Code for Frequency
  • A. Place Code
  • B. Frequency (Timing) Code
  • C. Pitch and Loudness Perception Place vs.
    Frequency Theory
  • IV. Place and Timing Information in the Central
    Auditory System
  • A. Auditory Pathways
  • B. Place Information
  • C. Timing Information
  • V. Physiology of Sound Localization
  • A. Interaural Time Difference
  • B. Interaural Intensity
  • VI. The Audibility Curve

4
Inner Ear
  • Main structure of the inner ear is the
    _______________

5
Cochlea
  • Three compartments
  • _________________________
  • _________________________
  • _________________________
  • Cochlear duct
  • formed by 2 membranes
  • _____________________
  • _____________________
  • cochlea functioning

6
Organ of Corti
  • The primary auditory receptor structure (15,000
    hair cells)

7
Transduction
  • Transduction occurs in the ____________ housed in
    the _______________
  • What causes stereocilia of a hair cell to bend?
  • Footplate of the stapes pushes the oval window
  • Causes motion in the cochlear fluid
  • Tectorial membrane

8
Hair Cells
  • There are two types of hair cells
  • _____________
  • _____________

9
Hair Cells
10
Auditory Nerve Fibers
11
Review
  • Auditory Perceptual Process

12
The Code for Frequency
  • Two major theories
  • ________________
  • _________________

Bekesy
13
Place Code Theory
  • Georg von Bekesy (1920s) vibration of the
    basilar membrane

14
Place Code Theory
  • Bekesy (1960s) properties of the envelope of
    the traveling wave
  • Envelope is peaked at ____ point on the basilar
    membrane
  • Position of the peak is a function of the
    ________ of sound

15
Place Code Theory
  • Further support
  • Culler et al. (1943) cochlear responses
  • Russell Sellick (1977) hair cell tuning
  • Kiang (1975) auditory nerve fiber tuning

16
Timing Code for Frequency/Frequency Theory
  • Rutherford (1886) neural firing rate
  • Wever (1949) volley principle
  • Rose et al. (1967) phase locking
  • _____________ neurons fire in synchrony with
    the phase of a stimulus

17
Pitch Perception
  • Periodicity Pitch the missing fundamental

18
Physiological Aspects of Loudness
  • How can nerve firing signal loudness?
  • When intensity increases
  • Neurons already firing saturate (above 40-50 dB
    SPL)
  • Neurons at other places on basilar membrane begin
    to fire more rapidly (pattern of auditory firing
    becomes broader)

19
Central Auditory System
20
Place Information
  • Place information is maintained through ________
    mapping
  • Auditory cortex has
  • ________ organization
  • Place code mainly
  • responsible for pitch
  • perception

21
Timing Information
  • Phase locking not maintained as move up through
    the auditory pathway
  • When phase locking occurs it is for frequencies
    below ________ Hz
  • Timing mechanism provides information about _____
    frequency sounds

22
Physiology of Sound Localization
  • ______________
  • Interaural time difference detector
  • ______________
  • Neurons responding to certain locations in space
  • Knudsen Konishi (178)

23
Audibility Curve
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