by Now Hear This

November 17, 2010

Squid can hear. Bats can’t, at least not well, near roads: traffic noise degrades the ability of nearby bats to hear the rustling of the beetles and spiders they prey on. Meanwhile, slow-moving wind turbines disrupt the animals’ echolocating abilities, such that the blades become (fatally) invisible or even attract bats because they resemble the “acoustic glints” of flying insects’ wings. Depending on the incoming signal, a bat’s neurons shift roles in concert — “It’s like a basketball team … like five guys on the court” — to highlight the sounds that a bat wants to hear while downgrading the less urgent noises. The nation’s loudest college-basketball arena — based on the building’s acoustics, its mid-court decibel level, and assuming a capacity crowd — is the University of Kansas’ Allen Fieldhouse. (“The rankings only show the potential of an arena,” says one of the Penn State acousticians that did the research. “If your arena is number two, you can overcome that by exerting more effort.”) The Mayan pyramids “were essentially echo machines,” designed to amplify voices, project music long distances, and “inspire spiritual feelings,” archaeologists now contend. People who work in noisy environments for more than a year and a half are at triple the risk of serious heart problems. To raise tax revenue, several municipalities are considering letting bars play music louder and later. (“New urbanism is great,” says Ted Rueter, the director of Noise Free America, “but who wants to live downtown when they can’t get to sleep till 3 in the morning.”) After analyzing the soundtracks of key scenes from some popular movies, bioacousticians at the Cornell Lab of Ornithology concluded that the film soundscapes resembled animal alarm calls. When bottlenose and Guyana dolphins swim together, one or the other — or possibly both — whistles in language that’s intermediate between the two species. (Dolphin Spanglish?) Researchers pinpointed the region of the brain that causes the McGurk effect, an auditory illusion whereby if you watch a video of one sound being spoken while listening to a second sound that’s dubbed over it, you’ll hear an altogether third sound. (More remarkably, a study last year showed that the McGurk effect can be induced simply by blowing puffs of air on the listener’s neck or hand.) People respond more positively to laughter when it’s made with the mouth open (“ha ha”) than with the mouth closed. The Emergency Broadcast Signal is coming soon to your cellphone: a new Broadcast Message Center will enable government agencies to send out geographically targeted text messages to warn of bad weather, evacuations, terrorist attacks, and other emergencies. Loud-clicking stinkbugs also communicate on a secret channel; when they buzz their abdomens near foliage, the plant stalks carry their calls several meters away to rivals and mates, undetected by potential predators. After listening to a Bengalese finch tweet 25,000 times in a soundproof room, scientists have devised a computer model that can predict the course of the bird’s notoriously complex song with high accuracy. Sonar may offer a better method of tracking oil spills, as it can monitor wide swaths of ocean and listen for bubbles of natural gas, which “ring like a bell when sound waves hit them.” Zion National Park became the first national park to adopt a Soundscape Management Plan, which proposes, among other things, to raise the “noise-free interval” — the average time between a human-caused sound, like an overflight or a leafblower — from three minutes to seven. Ears are the new fingerprints.