Ms. Frizzle and her class learn about vibrations and sound by playing with instruments and hitting objects. They not only hear and feel sound but see it using special glasses. Among many other lessons, they learn that high sounds are created by a fast vibration and low sounds are created by a slow vibration.
Daniel, a blind man, uses echolocation to perceive the presence of objects, just like Bats. A team runs him through some tests and find that he's able to create a mental image of his surroundings using sound.