The human ear can detect sounds within a certain range of frequencies. Explain how sound waves travel from the outer ear to the auditory nerve, and state what happens to the signal once it reaches the auditory nerve.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Sound travels as a longitudinal wave through the air and must be converted into electrical signals inside the ear before the brain can interpret it.
Model answer (5 marks)
The pinna of the outer ear gathers sound waves and directs them into the ear canal.
The waves reach the eardrum, a thin membrane, and cause it to vibrate.
The vibrations are transmitted to the three ossicles (malleus, incus, stapes) which amplify and oscillate.
The stapes pushes on the oval window of the cochlea, causing fluid in the cochlea to move.
Hair cells in the cochlea convert the fluid motion into electrical impulses that are carried by the auditory nerve to the brain.
The waves reach the eardrum, a thin membrane, and cause it to vibrate.
The vibrations are transmitted to the three ossicles (malleus, incus, stapes) which amplify and oscillate.
The stapes pushes on the oval window of the cochlea, causing fluid in the cochlea to move.
Hair cells in the cochlea convert the fluid motion into electrical impulses that are carried by the auditory nerve to the brain.
Examiner tips
- Use the word "vibrate" for the eardrum and ossicles; "oscillate" for the cochlear fluid. Mention the pinna and ear canal as the first step. Show the conversion from mechanical to electrical in the cochlea. State the final transfer via the auditory nerve.
- common_mistakes
- :
- Confusing the eardrum with the cochlea. Omitting the role of the ossicles. Failing to mention the conversion to electrical signals in the cochlea.
Mark scheme (5 marks)
- The outer ear (pinna) collects the sound waves
- Sound waves cause the eardrum (thin membrane) to vibrate
- Vibration of the eardrum causes the ear bones to oscillate
- Oscillations travel through the fluid-filled cochlea, where cells convert the vibrations into electrical signals
- The auditory nerve transfers the electrical signals from the cochlea to the brain
Key terms in this question
Related
- All WJEC A-Level Physics (Wales) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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