physics presentation

1. Range of hearing in
humans
S A T V I K S H A R M A , S I D D H A R T H
H A B B U A N D S I V E S H E U

2. The audible range for a human
stretches from 20 Hz to 20000 Hz (
one Hz = one cycle/vibration) .
Children under the age of 5 and
animals such as dogs and bats are
capable of hearing sounds of upto
200KHz

3. As the age increases, a person’s
ability to hear higher frequencies
decreases.
Here is a link to a video that will
that will show a progressive
increase in frequency try to hear till
the end.
https://www.youtube.com/watch?
v=1HcPAbZ6ptY

4. Infrasonic Sounds

5. Infrasonic sounds are low frequency sounds ranging
from 0Hz to 20Hz.
There are various sources for infrasonic sounds :-
A. Animals such as whales, elephants and
hippopotamus produce infrasonic sounds.
B. Natural events such as earthquakes, volcanoes,
bolides (meteors that explode in the atmosphere).
C. Vocalists such as Tim Storms can produce
infrasonic sounds.
D. Man-made made sources like sonic booms and
nuclear explosions produce infrasonic soundwaves.
Infrasonic sounds are harmful. They can cause intense
stress and lack of sleep with victims of it call ‘torture’.

6. Ultrasonic Sounds

7. Ultrasonic sounds are high frequency sounds above our range of
hearing ranging from 20KHz to anything above it.
Bats use ultrasonic sounds to locate their prey and navigate through the
darkness. Dolphins and porpoises use echolocation for hunting and
orientation. By sending out high-frequency sound, known as ultrasound,
dolphins can use the echoes to determine what type of object the sound
beam has hit.
Dogs have a hearing range that extends into the ultrasonic range. The
dog whistles have high frequencies which we humans cannot hear. This
helps the police and other related services as a silent caller for help from
their trained dogs. Ultrasonic sounds are used in sonography to create a
picture of the body and are safe for both the mother and the child.

8. SONAR

9. Sonar (sound navigation ranging) is a technique that
uses sound propagation (usually underwater, as in submarine
navigation) to navigate, communicate with or detect objects on or under
the surface of the water, such as other vessels.
It is used in many kinds of vessels. It is used in navy vessels to locate
potential threats. In fishing vessels, it is used for locating schools of fish.
Usually, there are two parts of a sonar, a transmitter and a receiver. The
transmitter sends “pings” these pings travel though the medium. If these
pings hit anything on their way, the rebound. The receiver receives the
pings. The receiver calculates the time taken for each ping to return. It
then creates the image based on the time taken.
In the modern SONAR versions, there is only one machine that sends
and receives.

10. Conclusion
We humans cannot hear everything, we have a limited
hearing range that extends from 20 Hz to 20KHz.
The sounds under our hearing range are called infrasonic
sounds and those above our hearing range are called as
ultrasonic sounds.
https://www.youtube.com/watch?v=1HcPAbZ6ptY