system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a big sheet of thin metal make wibbley wobbley sound?

As stated in the title, why do big sheets of thin metal make a wub wub sound when manipulated?
gpt
It's about resonance. Waves move across the sheet, like waves across the surface of water. These waves move from one side to the other, bounce off the far side of the sheet, and move back across. When the reflections match up - when a certain number of 'wave crests' fit across the sheet, they resonate. As these waves push the air around, they cause pressure waves in the air - sound.

The note, the tone, of these waves depends on how fast they move across the sheet. This is influenced by how stretched the sheet is. As the sheet wobbles, it is slightly stretched by a small amount. This slightly speeds up and slows down the waves moving across the sheet, making the pitch of the sounds they are making rise and fall. This is the 'wobbling' sound we hear.