the more energy a sound wave carries, the louder the sound and the bigger its... what?

The missing word is amplitude.

So the full idea is:

The more energy a sound wave carries, the louder the sound and the bigger its amplitude.

In simple terms, a higher-energy sound wave makes the air (or other medium) vibrate farther from its rest position each cycle, which is exactly what amplitude measures.

Quick Scoop

What’s going on physically?

• Sound waves carry energy as they travel through a medium like air or water.

• When a sound wave has more energy, it pushes particles farther from their normal position. That “how far” is its amplitude.

• Larger amplitude → greater intensity → we hear it as a louder sound.

You can picture two speakers playing the same note: same pitch (same frequency), but one is set to “volume 10” and the other to “volume 2.” The louder one is sending out waves with a bigger amplitude.

Mini FAQ

Is “amplitude” different from “volume”?

• Volume is how loud something seems to your ears (a perception).

• Amplitude is a physical size of the wave, which strongly controls that perceived loudness.

Does more amplitude always mean more energy?
Yes, for a given medium and frequency, more amplitude means the wave is carrying more energy.

Information gathered from public forums or data available on the internet and portrayed here.