CAN YOU HEAR ME?

CAN YOU HEAR ME?

The Magic called Sound

What is it like, when you accidentally press the mute button of your TV remote, while watching an electrifying cricket match? Even though you still can watch the match, you certainly lose interest in the game without sound. If this is so, then think of a time when the whole world will fall into a mute mode. No one can even contemplate a soundless world.

The world we survive is full of sound. The world we live in is full of sound. The chirping of birds, whistling of wind, roaring of animals, splashing of water- these are all parts of rhythms of nature. Not only natural sounds, but man- made sounds like the honking of horns too become an inevitable part of our lives. In short, man and sound are inseparable.

Sound is the music of life

Sound, in its simplest sense, is an energy made by vibrations.

When an object vibrates, it creates the movement in the air particles. These particles get in contact with others close to them, and make them vibrate too. As this continues, it becomes a bigger process, with more and more air particles bumping into each other. This movement creates what is known as sound waves. It keeps going until the object runs out of energy. We hear the sound when our ears are within the range of the vibrations.

The speed of sound

The speed of sound primarily depends on the medium through which the waves travel. For instance, sound waves travels faster in water, than in air. But in the medium of steel , it’s even faster . In an ideal gas, speed of sound depends only on its temperature and composition.

There are fixed rates for the speed of sound wave. In dry air at 20⁰C the speed of sound is 343 meters per second. Now takes the case of water. Here, sound travels four times faster, at an approximate rate of 1,484 m/s . But in solids like iron, it reaches around 5,120 m/s !

The speed of light is 2.99792458 x 10⁸m/s, almost 870,000 times faster than the speed of sound! This is the reason why you see lightning before you hear the thunder.

Why is it said that Super Sonic aircraft surpass the speed of sound?

Supersonic speed refers to a speed greater than that of sound. A bullet fired from a modern day gun is said to have this kind of speed. Another important example is the supersonic air craft. They are flights which travel faster than the sound that is audible to human ears.

An Indian example of Supersonic flight is the HAL Tejas, which is still in service.   

Star facts:-

·       Study of sound

Acoustics is the scientific study of sound waves.

·       Phobias

While ‘Acousticophobia’ refers to the fear of noise, ‘melophobia’ refers to the fear of music!

·       Smaller is louder

Smaller objects vibrate faster, creating higher frequency sounds. This is why the sound of your voice being higher than your father’s

·       New Science

Cymatics is a relatively younger branch of science that stu dies geometric forms created by Sound waves.

·       Loud Enough

Loudness depends on how loud or soft the sound is; it is measured in decibels (dB). It has been found that at 125dB, a sound becomes painful to human ears.

·       Healing Effect

One of the techniques that uses sound waves to heal wounds is the ‘MIST’ therapy.

Sound Level Meter

The Sound level meter, a hand held instrument with microphone, is commonly used tool for acoustic measurements.

·       Far- Reaching

It is said that whales communicate with each other underwater, their sound waves travel up to 800km.

Sound need medium to pass through

We know that, our Diwali crackers bursts with sound. But do we think such big explosions and collisions of the massive objects in space creates sound? Well, there are no sounds coming from them. The reason behind this strange phenomenon is that, there is no ‘medium’outside the the Earth to travel through. Air is not the only medium through which sound waves can travel. It can pass through liquid and solids too.

Hearing Range of animals varies greatly

As matter of fact, no two species of animals look alike,or behave alike.Similarly, the abilities and senses of animals vary too, from species to species.

One cannot expect a monkey to have the hearing ability of an elephant, nor can auditory ability between a marine mammal and terrestrial animal be compared. Generally, it is seen that larger animals hear and use low frequency sounds while smaller ones have with higher frequencies. However, there are always exceptions, as in the case of spadefoot toads that can easily pick up low frequency sounds. These animals live in desert habitats.

Similar to animals, birds and insects too have peculiar auditory features that help them adapt to surroundings.

Birds are known for their musical communication

How many of us have seen birds that don’t make sounds? Not many. Birds are in fact, most known for their ability to make sound, be it sweet chirping, or harsh caws.

There are different frequencies at which birds’ sound come out . There are others too that can sing at high frequencies, like warblers, sparrows, waxwings, kinglet etc. It is believed that one can never stop a bird from learning its own species’ song.

Sound around us

What is Ultra sound?

We have heard that most humans can hear the sounds between 20 and 20000 hertz. Ultra sounds are above this limit, or specifically above 20000 Hz. They are not different rom normal sound in terms of physical properties. But the only difference is that they can be heard and produced by only a few animals like bat, moth,dolphins etc and not by humans. In other words, the range of ultrasound begins where our sonic range ends.

The uses of ultrasound can be seen in electronic, navigational, industrial, medicinal and security applications.

Ultra sounds are useful in SONAR

SONAR is the short form for SOund NAvigation and Ranging. It is an ultrasonic system used in ships and other vessels for navigation, and locating objects underwater.

As we know, Sound waves travel faster than light through water. However , ordinary sound waves cannot travel longer distances , only ultrasonics waves can. Due to their high frequency and short wavelength, ultrasonic waves penetrate water to very long distances and it is this feature that is utilized in Sonar.

Fig. Illustration that shows the work of a SONAR

Ultrasounds are useful in medicine

Fig. Ultrasound scanning

Some of the important applications of ultrasonics can be seen in the field of medicine. Ultrasonography or ultrasonic scanning is one of it, which uses high frequency sound waves to produce images of internal organs, vessels and tissues. This type of scanning is used to diagnose the condition of organs such as liver, kidneys, gallbladder.

Then there is something called obstetric ultrasound. It is a technique used during pregnancy to create images of a baby inside the womb.

Another public health application of ultrasounds is dental care. It enables the equipment called ‘descalers’ to remove plaque from teeth.

Fig. Ultrasound Scanning machine

Noise, noise, everywhere

Noise pollution or Sound pollution refers to the term of excessive and troublesome sound that effects all living things on Earth. Commonly, noise is discussed in terms od decibels (dB), which is also the measure of loudness or intensity of sound. There are different kinds of noise around us today, and one of it is environmental noise. Roughly speaking, it is the accumulation of all the noise present in the specified environment

It is said that plants have the ability to control adverse effect caused by the noise pollution. Hence , grow more and more plants, thus we can stay healthy and present a beautiful , calm environment to our future.

SUBMITTED BY:

Thushara R B

Yogini E

Pradeep A

Sahana D

(Ist M Sc)

Reference:

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JOURNAL- JUNE 2017

INTERNET