Decibel

A decibel was a measurement of sound levels.

Regulations on Deep Space 9 restricted noise in Quark's to seventy decibels. Klingons were known to raise the decibel level when they visited the bar. 

When the Dominion occupied Deep Space 9 during the Dominion War, Jake Sisko noted that the decibels in Quark's were noticeable less than usual, attributing it to the presence of the Jem'Hadar in the bar. (SS DS9 (Three Sides to Every Story))