Search results
Results From The WOW.Com Content Network
Nonetheless, there are some early examples of what would today be considered civil defense. For example, as early as 1692, the village of Bedford, New York, kept on staff a drummer, whose responsibility was to sound the town drum in the event of a Native American attack—a very early precursor to the wailing sirens of the Cold War. [1]
Sound sample ⓘ A civil defense siren is a siren used to provide an emergency population warning to the general population of approaching danger. Initially designed to warn city dwellers of air raids (air-raid sirens) during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes (tornado sirens).
The city found out from neighboring jurisdictions that no sirens or early warning devices were activated or malfunctioning. Their suspicions of a different cause were confirmed.
In a pneumatic siren, the stator is the part which cuts off and reopens air as rotating blades of a chopper move past the port holes of the stator, generating sound. The pitch of the siren's sound is a function of the speed of the rotor and the number of holes in the stator. A siren with only one row of ports is called a single tone siren.
Rumbler siren. A Rumbler siren is a type of emergency vehicle siren used primarily in the United States.Developed in 2007 by Federal Signal Corporation, and sounding at a low-frequency level, it is designed to be heard by motorists who may otherwise be unable to hear high-frequency sirens due to ambient noise, such as urban traffic.
Discover the best free online games at AOL.com - Play board, card, casino, puzzle and many more online games while chatting with others in real-time.
A Federal Signal Modulator siren in Bay Head, New Jersey.. Federal Signal Modulators (also known as Modulator Speaker Arrays) are electronic warning devices produced by Federal Signal Corporation that are used to alert the public about tornadoes, severe weather, earthquakes, fires, lahars, tsunamis, or any other disaster.
A directional siren is a siren with a bandwidth broader than 500 Hz-1.8 kHz that enables listeners to more quickly locate the source of the sound. Generally, sound localization accuracy is within 5 degrees, but enabling improved accuracy, for example in an ambulance siren, can lead to faster identification and response, thus enabling an ambulance to reach its destination faster and increase ...