acoustics

This has been a good week for sonic physics. First came reports that scientists used sound waves to create a sonic black hole. Now, it seems that a different group of scientists have used specially calibrated sound waves to create something almost as cool: a sonic laser.

The lasers most people are familiar with are formed from beams of light with identical wave structures, added together to form one giant, coherent wave. The saser, created by scientists from the University of Nottingham, England, works the same way, but with correlated sound waves instead of light waves.

The world certainly isn't simple, and trying to express real-world dynamics in the form of an equation has long been a challenge. Realistic computer-simulated sound has been particularly tough to get right, and some of the hardest dynamics to recreate have been the movements and sound of water.

Scientists at Cornell have now announced a system that can look at a 3-D motion rendering of water--waves, drops, anything--and algorithmically create the dribbles, gurgles and plops it would be sounding, were it in fact real.

A new material created by researchers can refocus sound around certain objects and effectively render them sonically invisible to sonar. No natural material can do this, so man-made “metamaterials” must be created in order to toy with the laws of physics to essentially bend sound back on itself. Mind blown yet?

Apparently, Rupert Till, an expert in acoustics and music technology at Huddersfield University in northern England, knows where to find a good party. Till took a second look, or rather, a second hear, at the 5,000-year-old Stonehenge and discovered that its huge stone slabs reflected sound perfectly, making the site the perfect place to listen to repetitive, trance-like music.

MIT researchers have proposed a strange new way to predict the severity of a hurricane: Listening underwater. Currently, the most common way to gauge a storm's strength is to either study satellite images (which can be pretty inaccurate), or fly a weather plane straight on into the storm and gather critical data (which gets expensive).

Your kid borrows the car, blasts too many techno tracks, and blows out the subwoofer. It used to be that you´d have two choices: Buy a new one (woofer, not kid) or put up with a hoarse bass line. But when a subwoofer pops, it´s usually only the voice coil-the part that drives the cone-that´s burned out; the rest of the assembly is just fine. Boston Acoustics´s SPG555 subwoofer is the first with a replaceable voice coil that you can install yourself.