Here's why:

* Frequency and Pitch: Frequency refers to how often a sound wave vibrates per second (measured in Hertz). The higher the frequency, the more vibrations per second. Our brains interpret this as a higher pitch.

* Examples: A high-pitched whistle has a higher frequency than a low-pitched rumble of thunder. A piccolo plays higher notes than a tuba because it produces sound waves with a higher frequency.

Think of it like this: imagine a string on a guitar. If you pluck it gently, it vibrates slowly, creating a low-pitched sound. If you pluck it harder, it vibrates faster, creating a higher-pitched sound.

Key takeaway: Higher frequency = higher pitch.