Here's why:
* Frequency refers to how many wave cycles occur in a given amount of time. A higher frequency means more cycles per second, and a lower frequency means fewer cycles per second.
* Pitch is our perception of how high or low a sound is.
* Higher frequency sounds correspond to higher pitches, and lower frequency sounds correspond to lower pitches.
So, when you hear a sound getting higher, the frequency of the sound wave is increasing. When you hear a sound getting lower, the frequency is decreasing.
