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The Mosquito or Mosquito alarm is a machine used to deter loitering by emitting sound at high frequency. In some versions, it is intentionally tuned to be heard primarily by younger people. Nicknamed "Mosquito" for the buzzing sound it plays, the device is marketed as a safety and security tool for preventing youths from congregating in ...
Federal Signal Thunderbolt 1003 There are 8,200 alarm sirens for civil protection throughout Switzerland. They are tested once a year on the first Wednesday in February. [1] Sound sample ⓘ A civil defense siren is a siren used to provide an emergency population warning to the general population of approaching danger.
Alarm Will Sound is a 20-member chamber orchestra that focuses on recordings and performances of contemporary classical music. Its performances have been described as "equal parts exuberance, nonchalance, and virtuosity" by the Financial Times [ 1 ] and as "a triumph of ensemble playing" by the San Francisco Chronicle . [ 2 ]
Directional boring machine. Directional boring, also referred to as horizontal directional drilling (HDD), is a minimal impact trenchless method of installing underground utilities such as pipe, conduit, or cables in a relatively shallow arc or radius along a prescribed underground path using a surface-launched drilling rig.
From NFPA 72, 2002 Edition: “7.4.2.1* To ensure that audible public mode signals are clearly heard, unless otherwise permitted by 7.4.2.2 through 7.4.2.5, they shall have a sound level at least 15 dB above the average ambient sound level or 5 dB above the maximum sound level having a duration of at least 60 seconds, whichever is greater ...
It was reported that shortly after the events of September 11, 2001, the sound of many activated PASS devices could be heard beneath the rubble of the collapsed World Trade Center. [ 2 ] 343 firefighters (including a chaplain and two paramedics) of the New York City Fire Department (FDNY) were killed on that day.
However, in most fielded systems, unwanted clutter and interference sources mean that the noise level changes both spatially and temporally. In this case, a changing threshold can be used, where the threshold level is raised and lowered to maintain a constant probability of false alarm. This is known as constant false alarm rate (CFAR) detection.
A long-range acoustic device (LRAD), acoustic hailing device (AHD) or sound cannon is a specialized loudspeaker that produces sound at high power for communicating at a distance. It has been used as a method of crowd control , which has caused permanent hearing damage , having an extremely high decibel capacity (up to 160 dB measured at one ...