The incremental jumps in the numbers of decibels on the thermometer look small, but decibels are measured on a logarithmic scale because we can hear such a gigantic range of sound pressures. For example, the sound energy of a jet engine is approximately one billion times greater than the sound energy of a floor fan (50 to 140 dB SPL).

Decibels are logarithmic. Logarithms help to represent large ranges of numbers. For example, instead of counting from 1 to 1000 by 1 (1, 2, 3, 4, 5, 6….etc.), we can count by multiples of 10s (1, 10, 100, 1000). This is a logarithmic progression, based on powers (exponents) of 10. ​​So, if we write it a different way, it would look like this:

The decibel scale is a logarithmic scale that represents the HUGE range of sound pressures that we can hear. ​