We use two different forms of decibels in audio: the decibel scale which measures sound pressure level relative to human hearing, and units that measure either power or relative voltage level. The decibel (dB) scale sets zero as the lowest sound pressure level at which most people can hear a sound. Electrical signal strength is measured in units like the dBm, with “m” being short for milliwatt. Relative voltage level is measured in units like dBu and dBV. The “u” in dBu stands for unloaded.