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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 ...
The device works by emitting an ultra-high frequency blast (around 19–20 kHz) that teenagers or people under approximately 20 are susceptible to and find uncomfortable. Age-related hearing loss apparently prevents the ultra-high pitch sound from causing a nuisance to those in their late twenties and above, though this is wholly dependent on a ...
A late 19th-century speaking trumpet used by firefighters A small sports megaphone for cheering at sporting events, next to a 3 in (8 cm) cigarette lighter for scale. From the Ancient Greek era to the nineteenth century, before the invention of electric loudspeakers and amplifiers, megaphone cones were used by people speaking to a large audience, to make their voice project more to a large ...
As the saying goes, "good fences make good neighbors," but sometimes, your neighbors are just so damn cool that you want easier access to hanging out with your buddy next door. Thankfully, Natural ...
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 ...
This easy-to-use device was designed to help users stay connected with family, friends, and caregivers, featuring large icons, easy navigation, and support from 24/7 expert customer care.
"Some don't record, or some use a video device, but teachers have used phones in this way in the classroom for a while. I came across one recently and took it as my sign to go ahead with the idea ...
Its distinct tone of urgency, high sound pressure level (123 dB at 10 feet) and square sound waves account for its effectiveness. 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.