a dull roar
a dull roar
A low level of noise. Kids, when you work together, please keep it down to a dull roar.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
dull roar
n. a relatively quiet degree of noisiness. Try to keep it at a dull roar if you can.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.