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An air horn consists of a flaring metal or plastic horn or trumpet (called the "bell") attached to a small air chamber containing a metal reed or diaphragm in the throat of the horn. Compressed air flows from an inlet line through a narrow opening past the reed or diaphragm, causing it to vibrate, which creates sound waves .
In Germany and some other European countries, the pneumatic two-tone (hi-lo) siren consists of two sets of air horns, one high pitched and the other low pitched. An air compressor blows the air into one set of horns, and then it automatically switches to the other set. As this back and forth switching occurs, the sound changes tones.
All foghorns use a vibrating column of air to create an audible tone, but the method of setting up this vibration differs. Some horns, such as the Daboll trumpet, used vibrating plates or metal reeds, a similar principle to a modern electric car horn. Others used air forced through holes in a rotating cylinder or disk, in the same manner as a ...
Manual fire alarm activation is the process of triggering a fire alarm through a call point, pull station, or other device. This usually causes the alarm to sound the evacuation signal for the relevant building or zone.
The event was the first promotional ceremony attended by Police Commissioner Jessica Tisch in her new role as top cop and one insider said the horns left her visibly annoyed.
By Pete Schroeder (Reuters) -Major banks and business groups sued the Federal Reserve on Tuesday, alleging the U.S. central bank's annual "stress tests" of Wall Street firms violate the law.
The standard fire alarm sound used in most of North America. Coding refers to the pattern or tones a notification appliance sounds in and is controlled either by the panel or by setting jumpers or DIP switches on the notification appliances. The majority of audible notification appliances installed prior to 1996 produced a steady sound for ...
The former CEO of Abercrombie & Fitch (A&F) has dementia and late onset Alzheimer's disease, his legal team has said in a court document filed in New York. Lawyers for Mike Jeffries have requested ...