The decibel is a logarithmic ratio between two values, not an absolute amount — which is why it always needs a reference to mean anything. In digital audio the reference is full scale, giving dBFS; for true peak it is dBTP; for acoustic level in air it is dB SPL. The log scale matches hearing: a +10 dB change sounds roughly twice as loud, +6 dB doubles amplitude, and +3 dB doubles power. Working in decibels lets engineers add gains instead of multiplying them and compresses the enormous range between a whisper and a jet into manageable numbers. Misreading which reference is in play is a common, costly mistake.
