The [tag]Journal of the Acoustical Society of America[/tag] has an article about using microphones for [tag]landmine detection[/tag]. If you don’t have a membership subscription to JASA, you can read a summary at New Scientist, Cheap microphones listen for landmines.”

A major obstacle to clearing mines in poorer countries is the cost. In one method, mine clearers beam a low-frequency sound wave into the ground – which gently vibrates any buried mines – along with a radar beam. When the radar beam bounces off any vibrating mines it is reflected back at a different frequency. The problem is that radar sensors cost hundreds of dollars.

More information about the worldwide landmine problem can be found at the excellent website of The International Campaign to Ban Landmines.

[Am I going mad? I could swear I posted this two days ago…Nevermind. Don’t answer that.]