dBSPL (Decibels Sound Pressure Level)
Definition
A measurement of acoustic sound pressure level in the physical world, referenced to the threshold of human hearing (20 µPa). Used to measure speaker output, room noise, and environmental sound levels.
In Simple Terms
How loud something is in the real, physical world — not inside your computer, but in your room. Used to calibrate how loud your speakers play, so your mixing decisions are consistent.