Why is it zero if you hear something?
In: Technology
dB is a ratio so 0 is the base reference. +dB is an increase and -dB is a decrease. 0 is chosen and then adjustments are made from there.
So that is multifaceted question, but the simplest explanation to your question I think would be that 0dB while looking at a calibrated meter is a reference point. In a digital full scale meter for recording, going above zero would induce signal clipping.
dB is a logarithmic scale. Every time you add 10 dB, you make the sound ten times as loud. Every time you subtract 10 dB, you make the sound one tenth as loud. Zero dB is like multiplying the sound by 1: it’s just the original, unchanged sound, at it’s original volume.
In digital audio, 0 db usually means full scale audio. it should be listed as 0 dbfs. Decibels are a ratio between a reference level and a value. The full scale reference is the maximum possible level without clipping and distortion. That’s why it is so important. Normal levels are all negative values.
In analog, it is a certain power or voltage. Pro analog audio uses +4 dbm (0 dbm=1 milliwatt. Consumer audio uses -10 dbV.
dB is telling you how much louder to make something.
0 dB means dont make it any louder. Negative dB means make it quieter.