Soundproof stethoscope

Chelsea - There's no instrument more central to a doctor's toolkit than a stethoscope. That's why scientists at the Army Aeromedical Research Lab have designed a new kind that works in noisy conditions, like on a battlefield, in a helicopter, or in a stadium. Acoustical engineer Adrian Houtsma says it uses ultrasound-sound waves at a frequency of about two and a half million hertz. The human ear can only hear up to about twenty thousand hertz.

Adrian - And we realized that a helicopter may make a lot of noise, but there is no noise at 2.5 megahertz, so the two will not interfere with each other.

Chelsea - He says instead of listening passively to the heartbeat, the ultrasound stethoscope sends high-frequency sound waves into the tissue, listens as they bounce back, and then transforms them into sound the doctor can hear.

Adrain - It looks and sounds very similar to a regular conventional stethoscope, but internally it is something totally different. And if you listen carefully it sounds a little different.

Chelsea - In fact, he thinks more studies may reveal that the ultrasound stethoscope can hear details that conventional stethoscopes can't, like damage in a specific valve. That could make doctors look at this classic tool of medicine in a whole new light.

Bob - Thanks, Chelsea. If you ask your kids to turn down the volume on the TV while paying your bills, be careful: you might make more mistakes if you can barely hear it at all. This according to Boston University psychologist Takeo Watanabe and his colleagues. They asked volunteers to work on a simple computer task, while distracting dots darted around on the screen. And the volunteers performed worst when the distractions were too small to consciously notice. Brain imaging studies showed that these subliminal distractions mostly bypassed the prefrontal cortex, which filters out irrelevant information, and went straight to the brain's visual centers.

Takeo - As a result, the motion was processed, and resulted in disrupting the task performance more greatly.

Bob - So muting distractions without eliminating them may actually hurt productivity.

Chelsea - Thanks, Bob. Next time we'll be back to distract you with more science news from the States. Until then, I'm Chelsea Wald.

Bob - And I'm Bob Hirshon, for AAAS, The Science Society. Back to you, Naked Scientists.