The Ear as a Transducer

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The Ear as a Transducer
Introduction to Acoustics

• University of Salford
• Acoustics, Audio Video Group

2
Learning Outcomes

• Explain how the ear works acoustically
• Discuss the function of the outer, middle and
  inner ear
• Explain the concept of acoustic impedance

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Basic questions

• In what form does sound travel in air?
• In what form does information travel to and
  through our brain?
• What does a transducer do?
• What kind of transducer is the ear?

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Schematic diagram
Outer ear
Middle ear
Inner ear
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Why is it so complicated?

• Why 3 sections?
• The middle ear is an impedance transformer
• Impedance?! Transformer?! _at_!

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Impedance
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Impedance

• Any medium has a characteristic acoustic
  impedance
• Outer ear medium is air (low z)
• Inner ear medium is fluid (high z)

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Impedance transformer
malleus
stapes
Tympanic membrane
incus
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Conclusions

• The ear is a transducer, converting acoustic
  energy to (electrical) nerve impulses
• The inner ear is the transducer the middle ear
  is an impedance transformer
• Impedance z p/u