If a leaf falls in the forest and no one hears it does it make a sound?

Yes.

By definition, sound is: "mechanical vibrations transmitted through an elastic medium" (dictionary.com). Noise doesn't need to be perceived to be defined as "sound" since it is a mechanical entity.

However

The existence of the sound cannot be categorically proven unless heard (observed) or recorded, even though under the usual physical laws, it would be expected to occur.