Sound Of Music

Sound is what we hear; we know what a sound is.
When it comes from defining sound, let us go into basics of Physics, a little.
Sound is basically a ‘form of energy’. That is why, a huge sound, say a bomb blast could throw things around.

Next question is, how energy could become a sound?
Energy could be a sound or not (could be light, for an example), but these different forms of energy propagation has great difference in scientific properties, which are obviously beyond the scope of this writing. But basically we have to understand, why and when energy could become a sound.

Right; when we speak of sound, we should speak of a ‘sound source’. Sound source is a matter which produces propagation of energy. Imagine a steel string; when it vibrates, it produces sound. This is an every day example.
So what is a vibration? We know what a vibration is. If a body moves back and forth, we say it vibrates. When a body vibrates, it disturbs the medium around it.
Now, imagine a man swims in a swimming pool. His hands could be considered as a vibrating object, and motion of his hand could be considered as vibration, (though it is not exactly a vibration as the motion is not rapid). Motion of hands creates waves in water. These waves could be compared to what we mean disturbance. And the water is the medium.

In case of a vibrating string, air is the medium.

Let us consider picking a Guitar string. When you pick a string of Guitar, it vibrates. Vibration of the string creates disturbance in air, the medium. The disturbance is represented by wave transition in air.

When we bow a violin, the string vibrates both the sides. Vibration of the string is higher in the direction of bow.

When a drum kit is hit; again we generate vibration
Propagation of waves

Now, let us define few things. The body which vibrates is the sound source; vibration disturbs the surrounding, say air, is the medium
A medium could be air; water anything sound could be passed through by the form of waves.

A medium is considered full of invisible, tiny particles. When the vibration disturbs the medium, the particles move according to the vibration. This movement of particles creates a wave. This wave travels. So, to get a wave travelled, we need a medium that contains particles. That is why in vacuum, sound doesn’t get passed. In metals, sound wave passes in higher speed when compared to in air. That is why if lie down you could hear the sound of train in the track.

Now we are clear that sound passes thru a medium in the form of waves. And, the waves are nothing but the systematic movement of tiny particles of medium. Direction of movement of particles determines the type of wave. Particles could move back and forth or up and down.

So we get two basic types of waves. Wave that travels back and forth is the way the sound passes and let us not go much technical from here.

OK. We are going to touch acoustic physics when and where it is required. Now we have covered the basics of sound wave for completeness and with out which the proposed series would not be complete.

A good old movie? 

Music is essentially a sound but not every sound is music;
How music is defined? What is noise and what is music? We are going to deal this in next episode.