( the evolutionary pressures on them (2aA...)Dinosaur hearing, listening to muscle noise, quieter cubicles

LISTENING TO MUSCLE NOISE

Muscles make noise. For example, you can hear the sound of the masseter muscle--a jaw muscle used in chewing food-by propping your head (ear down) in the palm of your hand. The low rumbling comes from the shortening of the actomyosin filaments in the muscle fibers. Muscle noise can be measured using various sensors, such as microphones and even skin-mounted accelerometers. Scientists at the Scripps Institute of Oceanography listen to muscle noise in order to detect muscle stiffness, which in turn can provide information about neuromuscular disease, such as muscular dystrophy. Muscle stiffness was traditionally measured using external radiation sources (such as a vibrating piston). But the Scripps researchers use a process called passive elastography, a low-cost, in-vivo, non-invasive technique in which an array of surface sensors follow the passing of natural shear waves traveling along the muscle fibers. By the way, the Scripps scientists were originally interested in underwater noise effects and only later adapted their work to noise in muscle. (2pUW9; contact Karim Sabra, ksabra@mpl.ucsd.edu)

MEASURING VOCAL STRESSES IN TEACHERS

In classrooms, teachers need to speak frequently, and often loudly, risking occupational damage to their voices. How much do teachers actually speak in the course of a school day" Ingo Titze (ititze@dcpa.org) and Eric Hunter (ehunter@dcpa.org) of the National Center for Voice and Speech (Denver Center for the Performing Arts and also the University of Iowa) will present some detailed new results from a National Center for Voice and Speech data bank (containing nearly 6600 hours of voice data). The project tracked 31 teachers over two weeks and recorded their voices during all waking hours. The data
'"/>

Source:American Institute of Physics