Submitted by senpai_maccer t3_11xeku9 in askscience
Suppose for a sound wave in air, if its amplitude increases, that means the displacement of particles will increase from their undisturbed position.
Shouldn't that means larger compression and rarefaction, and thus, increased wavelength?
acquavaa t1_jd7001g wrote
If you pull a rubber band tighter, it snaps back faster. Same idea here. Whatever the equilibrating force is that is involved with the oscillation, it’s stronger if you increase the displacement from equilibrium. That stronger force causes the wave particle velocity change to keep pace with the peak displacement change, and so the period/wavelength is unchanged.