Regular stethoscopes are all well and good if you're working in a quiet country hospital where the only sounds audible are the quiet churning of some old Amish woman making butter on the front porch, but if you're out in the field and you need to hear someone's heartbeat it's a different story. Have you ever tried to use a stethoscope on a helicopter or perhaps in the pit at a Cannibal Corpse concert? No? Well it's no cakewalk, doc.
A new stethoscope for doctors in the field has been developed by Active Signal Technologies and the U.S. Army Aeromedical Research Laboratory that basically uses ultrasound technology to see and hear right into the human body, no matter what crazy crap is going on around them. It was created for use in Iraq in Apache helicopters, but I like to think some death metal bands might pick one up for their tour physician as well.
Noise-Immune Stethoscope [American Institute of Physics]