wash-out effect
n.— «In the early 1970s, manufacturers introduced sirens with different patterns and frequencies, to address a growing problem: Officers in different police cars using the same frequency often could not hear each other when approaching the same intersection, a dreaded phenomenon known as the wash-out effect that is a recipe for a crash. The yelp, the wail, the fast and the hi-lo sirens were born.» —“Earsplitting Symphony, With the Maestro in Blue” by Cara Buckley New York Times June 15, 2007. (source: Double-Tongued Dictionary)
Further reading
Martha recently found a 1938 letter that her grandfather sent to the local police chief in Virginia’s Shenandoah Valley. It concerns a suspected thief who her grandfather thought might be persuaded to confess because, he wrote,, the young man surely...
A firefighter named Steve in Newport News, Virginia, wonders why in his line of work, and for some police, certain additional kinds of days off after long unbroken shifts are called Kelly days, Kelly shifts, or Kelly time. The term most likely comes...