[GuiA]

Speakers and microphones are both transducers, which is what the author seems to be getting at.

[lostmsu]

But leafs shake because they receive waves. Not the other way around.

[CPLX]

Another valid metaphor though is that video of the leaves can be decoded the same way video of a speaker would. The analogy works either way.

[nkoren]

Yup. Interestingly, actual speakers work either way too. Reverse the polarity on them and you can use them as a crappy microphone.

[nkoren]

The sound is re-constructed from the shaking of the leaves. It's quite analogous to the way the sound is initially constructed from the vibration of a speaker membrane. The difference being that the medium of vibration which is used to propagate the "sound" is digital video rather than air.

[coldtea]

It's also the other way around. Leafs when shaken produce waves in return.

[Matumio]

You observe leaves shaking when there is wind (a correlation). To test for causality you need to make an intervention. You still the leaves - the wind keeps going. You block the wind - the leaves stop shaking. There clearly is an asymmetry here. The physical equations may be symmetric, but this doesn't justify calling a microphone "speaker".

[coldtea]

>The physical equations may be symmetric, but this doesn't justify calling a microphone "speaker".

Actually a speaker is just a microphone with very small adaptations depending on the use (polarity, noise sensitivity, etc).

But this is not about the wind, but about sound. The wind you describe is external ("You still the leaves - the wind keeps going"). But you can just as well have a wind produced by the leafs themselves.