Explain how sound waves are detected by the human ear and converted into signals that travel to the brain.

Eduqas A-Level Physics — 5.3 Electric and magnetic fields (A-Level only) · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (5 marks)

The pinna of the outer ear collects sound waves and directs them into the ear canal.
The waves reach the tympanic membrane (ear drum) and cause it to vibrate.
The vibrations are transmitted to the ossicles (malleus, incus, stapes) which oscillate.
The stapes pushes on the oval window, creating pressure waves in the fluid of the cochlea.
Hair cells in the cochlea convert these mechanical vibrations into electrical impulses that travel via the auditory nerve to the brain.

Examiner tips

  • Use the exact sequence of structures: pinna → ear drum → ossicles → cochlear fluid → hair cells → auditory nerve.
  • Mention the conversion from mechanical to electrical signals.
  • Keep each point concise and use correct anatomical terms.
  • Show the flow from outer ear to brain.

Common mistakes

  • Omitting the role of the ossicles or cochlear fluid.
  • Using vague terms like ‘sound travels’ instead of ‘vibrations’.
  • Failing to mention the auditory nerve as the signal pathway.

Mark scheme (5 marks)

  1. The outer ear (pinna) collects/gathers the sound waves
  2. Sound waves cause the ear drum to vibrate
  3. Vibrations from the ear drum cause the ear bones to oscillate
  4. Oscillations travel through the fluid in the cochlea
  5. Cells in the cochlea convert the vibrations into electrical signals which are sent to the brain via the auditory nerve

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