Umbrellas

I've been meaning to post this for an age and a half, so here goes.

The other day (now probably a month back), I was walking in a light rain, under my umbrella. As I was walking, I heard swish-swish, swish-swish coming from above me. I noticed that the swish-swish-es were in time with my steps, so I thought it may be the umbrella clasp swishing against the unbrella as I walked. I look at the clasp and it wasn't moving, so I discarded that explanation. So I thought, perhaps the rain is swishing off the umbrella with the up-and-down motion of my steps. I looked carefully and there really wasn't enough water on my umbrella to be doing that. So I was thouroughly stumped. I tried turning my umbrella different ways and all sorts, and couldn't figure it out.

Until I realised that the sound I was hearing was from my shoes, that had absorbed a bit of water and were somewhat squishy. Why was I hearing it from above me then? I can only assume that my umbrella was acting as a bit of a lens for the sound of my shoes, reflecting it back to my ears... so it sounded like it was coming from above.

Bizarre. Or can anyone else offer another explanation?