Decibels(dB)

• A decibel is a logarithmic unit of measurement. A logarithmic scale approximately matches the way humans perceive sound and light.
• It measures the magnitude of a physical quantity relative to a reference level.
• Noise floor, dynamic range and resolution are measured in dB.

Reference Levels

A reference level is a known physical measurement. If the reference level is known, the actual (as a opposed to relative) measurement can be resolved using the value in dB.

Often the abbreviation dB is followed by the reference level?