The decibel number and human perception of loudness greatly differs. It was visualized by type size and opacity of type. It would displayed around construction sites, subways, and/or places where there is large pedestrian traffic.

Db, Decibel

dec·i·bel

ˈdesəˌbel,ˈdesəˌbəl/

noun

a unit used to measure the intensity of a sound or the power level of an electrical signal by comparing it with a given level on a logarithmic scale.