They sent a sound wave with a frequency of around 800 Hertz (roughly the high g of a soprano) through the first waveguide and measured how well it was transmitted to the second and third waveguides.

Two engineering students of George Mason University in the United States have made a prototype of a sound device that can put ...

Deep in the Pacific, humans have tracked a mysterious whale’s call for decades—but no other whale seems to respond. And now, we might be running out of time to find the source.