Auditory Physiology

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Explain the function of the middle ear

The middle ear's major function is the conversion of sound from an air-filled medium to the fluid-filled inner ear. It accomplishes this by leveraging the larger surface area and the ossicles against the fluid-filled oval window.

Use this to explain what happens to hearing if fluid fills the middle ear

If fluid fills the middle ear, then sound would not be as able to conduct, since the large ear drum would not be as effective in translating sound through the ossicles to the oval window.

Explain how frequency is represented on the basilar membrane

If one unfirls the inner ear into a straight line, frequency is represented with the higher frequency being closer to the oval window and the lower frequency being further away from the oval window. This is true because varying parts of the basilar membrane respond differently to different frequencies

Some hearing aids stimulate the whole 8th nerve directly. Explain why these are not likely to be good hearing aids

What are the cues for sound location? Explain when each is used

Intensity Differences

  • Happen due to shadowcasting by the head
  • Shadows result in dulling of sound where the head has cast the shadow
  • Shadowcasting is more effectively used with high-frequency sounds than low-frequency sounds.

Timing Differences

  • When sounds hit one ear before another
  • influenced by the shape of the ear
  • This contributes to detecting whether a sound is above or below or infront or behind

Describe the role of the superior olive in sound localization

  • The superior olive is the first place in which sounds from both ears come together to be compared
  • Cells in the lateral superior olive look for intensity differences
  • Cells in the medial superior olive look for timing differences

Describe the columnar structure in the primary auditory cortex

  • Basilar membrane is mapped topographically onto primary auditory cortex
  • each column represents a sound of a particular frequency and spatial orientation (i.e., contralateral)

Where are the higher auditory language regions?

A2, Wernicke's and Broca's areas