Science Buddies: "Ask an Expert"

Hi
Does anyone know whether the same structure (say a concrete 50㎥ room) over ground, would have more intense echo had it been under ground?
If not what causes it?
And how severe is the difference?
thanks!

I know this question is old, but I thought it was interesting.

The amount a sound echoes depends on how much the material absorbs sound. So if you were to have a solid metal box, it would probably echo the same above and below ground, but a thin material would echo more underground. It also depends on where you are underground, since stone reflects sound a lot more than soil.

So you would almost always have at least a bit more of an echo underground, but the difference can range from almost nothing to a significant difference.