Question 3: the correct answer is In the ear. Got it right? Score 1 point.
Question 4 of 10
How many chambers does the human heart have?
Why, in question 3: Where is the smallest bone in the human body?
The answer is in the ear. The stapes, one of the three ossicles of the middle ear, measures about 3 millimeters. Together with the malleus and the incus, it carries the vibration of sound from the eardrum to the inner ear.
How sound becomes a signal for the brain
The inner ear contains the cochlea, a tube coiled like a snail shell and filled with fluid. Inside, thousands of hair cells move with the vibration and turn sound into electrical signals for the auditory nerve.
Each region of the cochlea responds best to a range of sound: the base to high-pitched sounds, and the tip to low-pitched ones. This is how the ear separates the notes of a piece of music.
Hair cells do not regenerate in people. That is why frequent exposure to very loud sounds, such as headphones at maximum volume, can cause permanent hearing loss.
The ear also takes care of balance. Near the cochlea are fluid-filled canals that sense head movements, and one explanation for seasickness and car sickness is the mismatch between these signals and what the eyes see.
