does sonar work?
is simply making use of an echo. When an animal or machine makes
a noise, it sends sound waves into the environment around it. Those
waves bounce off nearby objects, and some of them reflect back to
the object that made the noise. It's those reflected sound waves
that you hear when your voice echoes back to you from a canyon.
Whales and specialized machines can use reflected waves to locate
distant objects and sense their shape and movement.
range of low-frequency sonar is remarkable. Dolphins and whales
can tell the difference between objects as small as a BB pellet
from 50 feet (15 meters) away, and they use sonar much more than
sight to find their food, families, and direction. The LFA sonar
being tested by the military can travel thousands of miles, and
could cover 80% of the earth's oceans by broadcasting from only
four points. The frequency that both whales and the military use
falls between 100 and 500 Hz. Whales send signals out between 160
and 190 Db, the Navy has tested its sonar signals at levels up to