Hearing and Balance: Frequency, Place and Head Motion · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
En anglais

How the ear sorts pitch and motion

Science · The Human Body · ages 20-21
Name ______________________   Date ____________

  1. What bends the stereocilia bundles?

    • Blinking of the eyes
    • The tectorial sheet sliding as the membrane moves
    • Heartbeat vibrations only

  2. Where do high and low pitches bend the basilar membrane?

    • High at the base, low at the apex
    • High at the apex, low at the base
    • Both only in the middle

  3. The apex of the cochlea responds to the lowest pitches.

    Circle one:   True   False

  4. How do canals and otolith organs divide balance work?

    • Canals report rotation; otolith organs report tilt and straight-line motion
    • Both report only loud sounds
    • Both report only eye color

  5. Why is hair-cell transduction fast enough to follow sound?

    • Signals travel backward in time
    • Sound waves pause to wait
    • Bending directly gates ion channels

  6. Each ear carries how many semicircular canals? Type the count.

    Answer: ______________

  7. Disease kills the hair cells at the cochlear base. What hearing remains?

    • Total silence in all ranges
    • Only the highest notes survive
    • Highs fade, lows survive

  8. A student says the brain sorts pitch from identical nerve signals. What is wrong?

    • The brain never hears pitch
    • Cochlea sorts by place first
    • Nerves carry no signals at all
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How the ear sorts pitch and motion W1-mt_qzPAt9JMOZ-s1

  1. The tectorial sheet sliding as the membrane moves · Membrane motion slides the sheet, which drags the leaning bundles.
  2. High at the base, low at the apex · Frequency maps to place: base for high, apex for low.
  3. True · Twenty-hertz waves travel the full membrane to bend the apex.
  4. Canals report rotation; otolith organs report tilt and straight-line motion · Spinning fluid bends canal cupulae while sliding crystals weigh tilt.
  5. Bending directly gates ion channels · Mechanical tethers yank channels open with no slow chemical middle step.
  6. 3 · Three rings, one horizontal and two vertical, span all spin directions.
  7. Highs fade, lows survive · Base cells serve high pitches; surviving apex cells still report lows.
  8. Cochlea sorts by place first · Sorting is mechanical: each place fires only for its own frequency.
Worksheet · LightMySky