2. ULTRASONIC SOUND  The sounds having too high frequencies which cannot be heard by human beings are called ultrasonic sound or ultrasound.  In other words, sounds having frequency greater than 20,000 hertz are called ultrasound. Due to its high frequency, ultrasound has a much greater penetrating power than ordinary sound.

3.  Though human beings cannot hear ultrasonic sounds but dogs can hear ultrasonic sounds of frequency upto 50,000 hertz. This is the reason why dogs are used for detective detective work by the police. Bats,monkeys, deer, cats, dolphins, porpoises & leopard can also hear ultrasonic sounds. Children under the age of 5 can hear ultrasonic sounds of frequency upto 25,000 hertz. These days ultrasound

4. Applications of Ultrasound 1. Ultrasound is used in industry to clean “hard to reach ” parts of objects such as spiral tubes, odd shaped machines & electronic components, etc. The object to be cleaned is placed in a cleaning solution & ultrasound waves are passed into the solution. Due to their frequency, the ultrasound waves stir up the cleaning solution. Because of stirring, the particles of dust & grease sticking to the dirty object vibrate too much, become loose, get detached from the object& fall into solution. The object gets cleaned.

5. 2. Ultrasound is used to investigate the internal Organs of the human body such as gall bladder, pancreas, kidneys, uterus & heart, etc.  Ultrasound waves are used to investigate the organs inside the human body.  A Doctor can take the ultrasound scans of a person’s organs like liver, kidney, heart, etc.  It helps the doctor in the detection of stones in gall bladder, kidney & tumors in different organs &many other ailments. Ultrasound is also used for diagnosing heart diseases.

6. 3. Ultrasound is used in industry for detecting cracks or defects etc. in metal blocks without damaging them. Metal blocks are used in construction of big structures like buildings, bridges, machines &scientific equipment, etc. There may be some flaws or defects inside the metal blocks which are invisible from outside. The use of such metal blocks having internal cracks reduces the strength Of the structure to be constructed. The internal cracks in the metal blocks are detected by using ultrasound. This is based on the fact that an internal crack does not allow ultrasound to pass through it. It reflects the sound Ordinary sound waves cannot be used for detecting the flaws in metal blocks.

7. 4. Ultrasound scans are used to monitor the development of unborn baby inside the mother‘s uterus.The ultrasound scanner transmits ultrasound into mother ‘ body & receives echoes formed by the reflection of ultrasound from Inside. The ultrasound echoes form a picture of the developing baby on a monitor which helps the doctor to keep a track of the developing baby.

8.  Thus, ultrasonography is used for the examination of unborn baby during pregnancy to detect any growth abnormalities. The ultrasound method is a safer way of checking whether the is developing normally or not than using X- rays because X rays can damage the dedicate body cells of the unborn baby.