Zero decibels (0dB) is the average threshold of hearing for the healthy adult ear.
The units of this logarithmic scale are called Bells (after Alexander Graham Bell.
- 0Bells, 1Bells, 2Bells, 3Bells, 4 Bells, etc.
Of course, nobody uses this scale now because the units are too large, just like one dollar is too large for many things we want to purchase. Hence, just like one dollar is broken up into 10 dimes, one Bell is equal to 10 decibels (dB). This is the unit
- 0dB, 10dB, 20dB, 30dB, 40dB, etc.
A person with a hearing level at 4 Bells (40dB), would require a tone 10,000 times more intense than a person with a normal threshold (0 dB).
At 3 Bells (30dB), the tone would have to be 1,000 times more intense.
At 2 Bells (20dB), the tone would have to be 100 times more intense.
At 10 Bells (10dB), the tone would have to be 10 times more intense.