amplitude
introduction
Amplitude is a factor related to how loud a sound is.
text
simple explanation from a maker of soundproofing products: https://www.soundproofcow.com/characteristics-of-sound-wave/
another from equipment retailer Sweetwater: https://www.sweetwater.com/insync/amplitude/
video
a visual comparison of soft and loud sounds: https://www.youtube.com/watch?v=vVaq8OlxkL4
brief video relating it to what we learned about the nature of sound (also previews frequency): https://www.youtube.com/watch?v=-_xZZt99MzY