Sound

You might know that sound is created by vibration. Sound requires a medium for propagation. A vibration can be considered as a periodic back and forth movement of an object. The frequency of vibration is the number of vibrations that happens in one second. So if something vibrates faster, there will be more vibrations in one second and hence the frequency is higher. Shrill sounds are characterised by high frequency and deep sounds are characterised by low frequency. Human ears can hear only the sounds that are between 20Hz to 20000Hz, where a Hertz(Hz) refers to one vibration per second.

When air is pushed through the vocal cords it vibrates producing a sound. In many contexts, the words 'pitch' and 'frequency' can be used alternatively. Each object when vibrating in its natural form produces a sound which is called its natural frequency. Depending upon the physical dimensions of each object the natural frequency could change. During a simple vibration, the resulting sound would mostly have its natural frequency and it may also have sounds that are in multiples of natural frequency. An object can vibrate twice, thrice or a few times faster/slower than its natural mode, but its unnatural to vibrate in any frequency in between these values without a change in physical dimensions! The frequencies that are multiples of the frequency are collectively known as 'harmonics'.

Now take a deep breath and say 'saaaaaaaa...' and extend the 'aaa' sound as much as you can without any disturbance in the sound. Make the sound as natural as possible with least strain. Congratulations !! you just sounded in your natural frequency ! This can be roughly equated with the term 'kattai' in (carnatic) musical terms. This sound varies from person to person. In an adult male this frequency averages about 125 Hz, adult females around 210, in children the frequency is over 300 Hz.