Understanding Sound and Equilibrium

Introduction

• Focus on the mechanics of hearing and equilibrium.
• Exploration of how sound is perceived and how balance is maintained.

What is Sound?

• Sound is vibrations in the air.
• These vibrations beat against the eardrum.
• Vibrations are transmitted through tiny bones, moving fluids, and triggering hair cells.
• Sound is interpreted by the brain through neurons sending action potentials.

How Sound Works

• Vibration: Key to sound transmission.
  • Vocal folds, guitar strings, or other objects create vibrations.
  • Air particles vibrate, creating sound waves.
• Sound Waves:
  • Frequency: Number of waves passing a point in a given time.
    • High-pitched: Short, quick waves.
    • Low-pitched: Longer, slower waves.
  • Amplitude: Determines loudness.

Ear Anatomy

• Divisions: External, middle, and inner ear.
  • External and middle ear: For hearing.
  • Inner ear: For hearing and balance.

External Ear

• Pinna (Auricle): Catches and funnels sound waves.

Middle Ear

• Eardrum (Tympanic Membrane):
  • Boundary between external and middle ear.
  • Vibrates in response to sound waves.
• Auditory Ossicles:
  • Malleus, Incus, Stapes (Hammer, Anvil, Stirrup): Amplify sound waves.
  • Conduct eardrum vibrations to the inner ear.

Inner Ear

• Labyrinth:
  • Complex structure responsible for hearing and balance.
  • Cochlea: Converts vibrations into electrical impulses.
  • Basilar Membrane: Reads sound frequencies.
  • Organ of Corti: Contains sensory and nerve cells.
• Hearing Process:
  • Pressure waves move through cochlea fluid.
  • Basilar membrane vibrates at specific frequencies.
  • Different membrane sections correspond to different pitches.
  • Hair cells in the organ of Corti transduce sound into electrical signals.

Equilibrium and Balance

• Vestibular Apparatus: Detects head movement.
  • Uses fluid and hair cells, similar to hearing.
  • Semicircular Canals: Detect different head rotations.
  • Utricle and Saccule: Sense fluid motion, informing the brain.
• Balance Process:
  • Brain interprets head movement via hair cell signals.
  • Motion sickness occurs when sensory inputs are conflicting.

Conclusion

• Review of how sound is transduced into action potentials.
• Overview of equilibrium maintenance.
• Acknowledgement of contributors and support for educational content.