A person walking down the street can quickly use acoustic cues to locate, say, the
position of a car approaching from behind or of a radio blaring from an open
window. The blast of the car's horn reaches the ear nearest the car first, and the
deejay's booming voice sounds slightly louder in the ear nearest the radio.
With training, people can improve on such sound perceptions, but some basic
acoustic skills respond far more than others do, a new study suggests. Volunteers
given extensive practice became progressively better at perceiving slight
differences in the loudness of sounds delivered simultaneously to their right and
left ears, say Beverly A. Wright and Matthew B. Fitzgerald, both neuroscientists
at Northwestern University in Evanston, Ill.
Yet given just as much practice, other trainees exhibited only modest gains in
their perception of subtle alterations in the timing of equally loud sounds