BBC: Only one in 10 000 people have perfect pitch—the ability to identify a given musical note without the help of a reference note. Although long believed to be innate, perfect pitch may not be so perfect after all, say Howard Nusbaum of the University of Chicago and his colleagues. In their paper published in Psychological Science, the researchers discuss their study in which they played a long piece of music to a group of 27 people with perfect pitch. Over a period of 45 minutes, the researchers gradually turned the tones slightly flat. Not only did the change go unnoticed, but when the tones were returned to normal, the listeners claimed they sounded too sharp. The researchers determined that the ability to recognize pitch, rather than being absolute, can change with listening experience. Next they hope to see whether adults without perfect pitch can improve in their ability to recognize notes.

Science: Scientists have long puzzled over how such a small animal as a cicada can produce such a deafening drone. Now Derke Hughes of the US Naval Undersea Warfare Center and colleagues have used microcomputed tomography to image the tiny noise-making structures, called tymbals, that are on either side of a cicada’s abdomen. Each of a cicada’s two tymbals consists of a series of microscopic ribs connected by a membrane. Unlike many insects, which make noise by rubbing body parts together, cicadas cause the tymbals to vibrate. They pull the tymbals’ ribs together and then allow them to snap apart some 300–400 times per second, and the sound is amplified by the creatures’ hollow abdomen. Some cicadas can produce sounds up to 120 decibels—loud enough to cause hearing loss in humans. The investigators hope to use their study of cicadas to improve current sonar systems for underwater exploration.

BBC: The greater wax moth has been shown in a recent study to be able to detect some sounds with frequencies up to 300 kHz. In comparison, humans top out at 20 kHz and dolphins, which can communicate in ultrasound, at 160 kHz. The study was led by James Windmill of Strathclyde University in Glasgow, Scotland, who says the moths may have evolved the capability as a defensive response to predatory bats, which employ ultrasound to communicate. Ultrasound waves degrade quickly when traveling through air, so a better understanding of how moths utilize the frequencies might help Windmill ‘s team and other scientists in the development of microacoustic devices such as miniature microphones.

Ars Technica: Humans hear by using their ears to detect vibrations and their brain to translate those vibrations into nerve inpulses. Most models of human hearing assume that the sound measurements made by the ear and brain are linear. The result is a direct correlation between the abilities to accurately determine the frequency and the duration of a sound. Such linear models are used in modern audio compression algorithms to save space by removing presumably inaudible tones. To fine-tune the model, Jacob Oppenheim and Marcelo Magnasco of Rockefeller University in New York tested the ability of subjects to determine both the frequency and duration of so-called Fourier-limited sound pulses. Such pulses are pairings of specific frequencies and shortest possible durations that together result in the minimum amount of uncertainty possible according to linear models. The researchers found that across the board the test subjects outperformed by a factor of 10 the linear model’s predictions for ability to determine the sound pulses’ frequency, duration, or both. Better understanding of the way that humans detect sound may produce audio compression algorithms that improve sound quality and don’t cut out parts of the sound that people can actually hear.

Science: Dolphins, which are known for their complex cognitive and social behavior, appear to be able to call each other—by whistling. Stephanie King of the University of Saint Andrews in the UK and her colleagues studied recordings made by the Sarasota Dolphin Research Program of 250 wild bottlenose dolphins that were briefly captured between 1984 and 2009; they also looked at 4 captive dolphins. All dolphins have their own distinctive whistle, learned from their mothers. But the dolphins in the study also could imitate the whistle of their closest social partner—such as mothers and their calves, or allied males. “They produce the copies when they are separated, which we think shows that they want to reunite with a particular individual,” said King. Now her group hopes to expand its study beyond captured dolphins to see how dolphins use their whistling ability in the wild.