[ELI5] How does something reach negative decibels?

Question

Microsoft made a -23 decibel room, but how does that work exactly? Once something hits 0 decibels how exactly can we measure it getting more quiet than that?

In: 24

Answer 1

decibels are often used to describe relative measurements or changes in measurements as well as absolute measurements (where a fixed value is 0dB). In which case it could be that there is 23 dB of loss (~200x smaller) of a signal from the outside of the room to the inside of the room. It could be that there is 23 dB of loss from a signal in the center of the room, bouncing off the walls and measured again at the center of the room.