the effects of a solids dimensions on sound waves?

schneevva

I've been thinking, what sort of effects would changing the dimensions of a solid, (lets say a block of wood, or plank.) have on the sound waves passing through it.

For example, lets say I take a block of wood, and reduce the mass and surface area (I.E cutting the ends off a plank)? or cut a cone shape into the board? I'm fairly certain the second will make the sound louder, but why? is it because I increased the amount of board that has contact with the air? or perhaps because I decreased the amount of wood that the sound wave has to travel through? maybe both?