Ultrasounds and why they are helpful to humans

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EXTENDED ESSAY

Ultrasounds and why they are helpful to humans

Ivan La Bruna

D #0261-011

American School of Milan

IB Extended Essay

May 2003

Word Count: 3770

Abstract

Ultrasounds are sound waves that exceed the limit of human hearing. In latin ultrasound means that it goes beyond a boundary, in this case the sound wave goes over our hearing capacities. The study of sound waves could be considered ancient study because sound was always an interest of the people. This is why people created many musical instruments in different areas, the most curious thing is that the shapes differ from location and also produce different sounds. Without these studies on sound scientists or explorers probably would have not reached the level of wave reproduction there is in modern times. In the past sound waves were reproduced with wind and string instruments while in modern days scientists are able to create a sound wave with specific requirements.

What will be discussed in this essay will be an explanation on what aer ultrasounds and why they are applied to society. Ultrasounds are used mainly in the medical environment but also in detecting the distance of objects, on submarines, and other uses which will be discussed. The good thing about ultrasounds is that they are not very expensive and for this reason it has expanded more and more. For example ultrasounds are used in the medical world to scan the fetus in the womb of a woman, thanks to this equipment the doctors are able to control the fetuses health without harming the fetus and not making the client pay expensive bills. The positive aspect of ultrasounds is that by using a moderated frequency it does not harm the skin tissues of our body nor other organs, it is a safe method to image parts of our bodies without harming them, this is why it is used so often.

Ivan La Bruna

Table of Contents

Abstract

2

Background

4

Introduction

9

How it is produced

1

How it works

3

What is it used for

6

Conclusion

8

Bibliography

20

Background

Humans, as other living beings, have the capacity to hear and to listen what sorroundings them. With this ability, civilized humans, started to study sound and how it behaved. The study of sound could be considered one of the most antique studies existing, people have always curioused on how to produce new sounds. The voice was explored continuosly, people started in producing new sounds with their voice and changing the tone of it in order to produce different melodies, learning how to control their vocal cords. The reproduction of sound is a natural isntinct for humans, people noticed that by changing their voice they were able to transmit some information to another person such as anger or exitement. Humans are able to have a voice because our body developed vocal cords which vibrate at the rate that we decide, the more the speed of vibration of the cords are changed, the higher the pitch. The vibration of vocal cords then becomes our voice, and when the human race has evolved to modern times, they were able to have a form of communication called language which makes the communication between people much better. But once that the human race was able to have language they still continued their studies such as making instruments.

The exploration of sound is one of the areas that have interested people the most especially because they could make instruments that produce different sounds, the first instrument might be thought as the mouth because it was the first thing with which man was able to use to reproduce sound. People started to make different instruments because they understood how to reproduce sound. The most popular instruments were based on the air blown in them and by having strings vibrating. For example a guitar has six strings, each string will produce a different sound because of its vibration, the vibration gives the sound wave a specific speed. Considering that two strings are aside with same thickness but different length, if they are plucked in the same place then they shorter string will produce a higher pitch than the longer string. Manufacturing instruments brought people to actually pay attention to the vibration process and noticed that it was an important factor on the outcome sound but they never went in deeper technical study as modern days. The actual study of the speed of sound came much later in time, and only in modern days people were able to understand that what we heard was affected by the speed of sound and by the amplitude. People such as Daniel Colladen who attempted to calculate the speed of sound in water in 1822 was one of the first pioneers in ultrasounds without any great discovery. In 1880 Pierre Curie and Jacques Curie discovered that by applying pressure on a quartz crystal thus would generate an electrical impulse that would deform the crystal and vibrate at a very fast rate. The quartz would generate high sound frequencies or else called ultrasounds that couldn't be heard by the ear.1

People started to use ultrasounds for the benefit of people when, in 1912, the Titanic sank and killed a large amount of children and women because of an unwarned iceberg. Scientists immediately thought of creating a device that would prevent a disaster similar to the titanic incident, the device would have allowed ships to detect any dangers such as icebergs or any other floating menace on the ocean. In 1914, Reginald A. Fessenden built the first functional sonar which was also used by submarines in the First World War, thus would detect floating icebergs and also enemy submarines to attack them. The sonar was also called 'hydrophone', the problem with these early devices was that they only had the capacity to perceive signals and not to emanate nor send sound signals. 2
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After the First World War scientists made another great development in ultrasound technology, an ultrasonic metal flaw detector was constructed which was used to detect the integrity of the materials in ships during the battles. Once that scientists and doctors notices that ultrasounds could be used for the benefit of the people, because parts of bodies could be mapped, scientists explored the new area creating new equipment and being pioneers in the field they were gaining a lot of information. By 1985 Japanese doctors had equipment that had real time mapping of the subject diagnosed seen in a ...

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