Take several identical bowls and pour water of different heights into them. The tone will become louder with the height of the water. Finally, tap it with chopsticks to create music.

The level of sound frequency is called pitch, which is one of the three main subjective attributes of sound, namely volume (loudness), pitch, and timbre (also called timbre).

The pitch is also related to the structure of the sound emitter, because the structure of the sound emitter affects the frequency of the sound. (So ??the material of different bowls will affect the difference in music)

Reference tone-Baidu Encyclopedia