Acoustical Society of America

Without words, bullfrogs communicate through stutters in their croaks

Male bullfrogs communicate with other bullfrogs through calls made up of a series of croaks, some of which contain stutters, according to a new study which describes a pattern not previously identified in scientific literature. Researchers recorded 2,536 calls from 32 male bullfrogs in natural chorus and analyzed the number of croaks in each call and the number of stutters in each croak. It is known that the male bullfrog’s call attracts females for mating, maintains territorial boundaries with other males, and indicates that the frog is healthy and aggressive.

Time-reversal acoustics research promises medical breakthroughs

Scientists have not yet found a way to actually make time run backward, but in the cutting-edge world of recent acoustics research, they have shown a way to make sound waves run backward in a kind of ultra-focused reverse echo. By the technology known as time-reversal acoustics, sound waves – in exact reverse order from the original sound – echo directly and very precisely back to their source point. The technology promises a wide array of applications, including medical applications such as ultra-precise medical imaging, diagnostic techniques using ultrasound, incision-free surgical techniques, and even the potential for a method of recharging the batteries of implanted devices like pacemakers without performing surgery.

Expendable microphones may help locate building collapse survivors

Data gathered by Penn State engineers in a volunteer effort at the World Trade Center tragedy, suggests that simple, inexpensive microphones dropped into the rubble of a collapsed building may be able to aid search and rescue teams despite ground level noise.
Dr. Thomas B. Gabrielson, associate professor of acoustics and senior research associate at Penn State’s Applied Research Laboratory, says, “In conventional survivor searches, noise generating activities at the surface must be stopped while listening for survivors.”
However, the Penn State team found that the noise level in the interior voids of the rubble was about the same as that of a quiet residential neighborhood even though the noise level at the surface was much higher due to constant operation of three heavy lift cranes, air hammers, and dozens of rescuers workers.