( The following items describe some high...)Dinosaur hearing, listening to muscle noise, quieter cubicles

The following items describe some highlights from among the many papers being given at the meeting. Full abstracts of the presentations mentioned below can be viewed at the ASA Meeting Abstracts Database (http://asa.aip.org/asasearch.html) by typing in the last name of the author or the appropriate paper code. Entire sessions can be accessed by typing in the session code followed by an asterisk (e.g., 2aAB*).

PALEOHEARING--HOW DINOSAURS HEARD THEIR WORLD

Studying the auditory systems of living organisms is helping scientists to learn the evolutionary pressures their ancestors faced, and even to reconstruct the hearing abilities of extinct animals such as dinosaurs and early mammals. According to the University of Maryland's Robert Dooling (dooling@psyc.umd.edu), the inner ears of archosaurs (birds, crocodilians, and extinct dinosaurs) have highly similar structures. The researchers found a relationship between the body mass of a species and the size of a sensory structure in the inner ear known as the basilar papilla. Small, lightweight species with a short basilar membrane can hear higher frequencies than larger species with a longer basilar membrane. Analyzing these and other variables, the researchers suggest that large dinosaurs could mainly hear low frequencies, with a high frequency hearing limit below 3 kHz. For comparison, this is around the upper frequency limit of a conventional telephone; humans speak at frequencies as high as 8 kHz and can hear up to about 20 kHz (2aAB2). Other papers in session 2aAB will explore how the middle ear of mammals evolved as they made the transition from water to land (2aAB3), the identification of over 20 specialized structures that may have enhanced the hearing of various fish species during their evolution (2aAB1), and the notable features of 36 cat species' middle ears, which may provide clues on
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Source:American Institute of Physics