A decibel is the degree of pressure increase – or the amplitude – which corresponds with the loudness of a sound. The higher the pressure, the louder the volume. Converting to the human ear, it is indicated as the decibel unit.
To produce a pressure increase there first needs to be some kind of energy or power inflicted on the medium.
Now don’t be intimidated by this formula, or the fact that there is a logarithmic involved in it. We shall see that it is not as difficult as it looks. We are going through the equation starting at the beginning:.
One to the negative twelve! This is incredibly small, we are talking about one trillionth of a watt. Can you imagine how unbelievable sensitive the human ear is?. On the other side of the spectrum, the loudest intensity which a human is capable to hear is one (1) watt per square meter. Intensities higher than this will start to hurt. You can see that there is an enormous gap between the softest and the loudest intensity we can hear. From 0.000000000001 to 1, that is why we use logarithmic to convert really big numbers into small, easy-to-interpret numbers.