Run your finger across the top of your keyboard, starting at the “q” and finishing at the “\”. Run your finger the other way. Listen to the sound it makes. Run your finger over the tops of the keys faster and the pitch goes up. Run your finger more slowly and the pitch goes down.
You are witnessing an amazing process of synthesis in your brain. There is no pitch out in the real world, just a series of short and sequential air-molecule vibrations. Your brain takes these little clicks and, depending on how fast their coming in, translates them into a melodious sound. Your brain wants to hear pitch.