In school our teacher sayd that certain sound HZ can cause fear, headache and brain stopping.. http://www.bwgen.com
when I listened to these sounds I did have a headache..
or it could of been my mind :P
well anyway, human ears cant hear under 20-25hz but your body can sense it.. try it.
-edit- found some intresting stuff:
The military use of infrasound dates back to the First World War, when the detection of such frequencies helped pinpoint the enemy
