Auditory Physiology and Hearing

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PSY 3520 Sensation and Perception
Auditory Physiology and Hearing
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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?

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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

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The Stimulus for Hearing

• Our perception of sound depends on the vibration
  of objects, which cause __________________________
  ______

Compression
Compression
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The Stimulus for Hearing

• Graphically

compression
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Pure Tone
_________
_________
________ _________
________
____________
_________
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Pure Tone

• Frequency (_____) ________________
• ___________________________________
• 100 Hz 100 cycles per second
• 1,000 Hz 1,000 cycles per second
• Amplitude (___) ___________________
• ___________________________________
• ___________________________________

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Decibels

• dB 20 log (p/po)
• p amplitude pressure of the sound wave
• po reference pressure which is set by
  experimenter
• Usually 0.0002 dynes/cm2
• SPL (sound pressure level) used to indicate
  this reference pressure was used
• 50 dB SPL

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Perceptual Dimensions of Sound
Physical Dimension Perceptual Dimension
__________________ ___________________
__________________ ___________________
______________________________________ ___________________
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Complex Sounds andFourier Analysis

• __________ regular repetition of pressure
  changes
• __________ breaking
• a repetitive waveform into a
• number of sine-wave
• components

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Fourier Analysis
Fundamental frequency
3rd harmonic
5th harmonic
_______________ the ear analyzes tones into
their simple components
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Structure and Function of the Auditory System

• 3 sections of the ear
• Outer Ear
• Middle Ear
• Inner Ear

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Outer Ear

• ____________ fleshy part of the ear
• Helps in sound location
• Channels sound waves to the auditory canal

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Auditory Canal

• Channels sound waves to the eardrum
• ___________ enhances the intensities of certain
  sound waves (2,000-5,000 Hz)
• Protective function
• Wax in the auditory canal
• Keeps eardrum at a constant temperature

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Eardrum (Tympanic Membrane)

• Vibrates in frequency with sound waves

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Middle Ear

• ________
• Malleus Hammer
• Incus Anvil
• Stapes - Stirrup
• Two Major Functions
• Increase pressure applied to oval window
• Protective function

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Functions of the Ossicles

• Increase pressure applied to the oval window
• Conduction deafness
• Two ways pressure increased at oval window
• Protective Function

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The Eustachian Tube

• Pressure Regulation regulated by an opening in
  the back of the throat (_____________)
• Tube can be opened two ways _______ or
  ___________
• _____________ middle ear pressure greater than
  outside air pressure
• _____________ middle ear pressure lower than
  outside air pressure

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Inner Ear

• Main structure of the inner ear is the
  _____________

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Cochlea

• Three compartments
• _________________
• _________________
• _________________
• Cochlear duct
• formed by 2 membranes
• __________________
• __________________

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Organ of Corti

• The primary auditory receptor structure (15,000
  hair cells)