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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 ...
Ululation (/ ˌ j uː lj ʊ ˈ l eɪ ʃ ən, ˌ ʌ l-/ ⓘ, [1] [2] from Latin ululo), trilling or lele, is a long, wavering, high-pitched vocal sound resembling a howl with a trilling quality. It is produced by emitting a high pitched loud voice accompanied with a rapid back and forth movement of the tongue and the uvula. [3]
It is the property of sound that most determines pitch. [1] The generally accepted standard hearing range for humans is 20 to 20,000 Hz. [2] [3] [4] In air at atmospheric pressure, these represent sound waves with wavelengths of 17 metres (56 ft) to 1.7 centimetres (0.67 in).
The idea was born after he was irritated by a factory noise when he was a child. [6] The push to create the product was when Stapleton's 17-year-old daughter went to the store to buy milk and was harassed by a group of 12- to 15-year-olds. Using his children as test subjects, he determined the frequency of "The Mosquito". [7]
An unexplained high-pitched tone has kept residents of a Portland suburb awake at night for at least a week.
Block diagram of the signal-flow for a common feedback loop [1]: 118 . Audio feedback (also known as acoustic feedback, simply as feedback) is a positive feedback situation that may occur when an acoustic path exists between an audio output (for example, a loudspeaker) and its audio input (for example, a microphone or guitar pickup).
Electric traction motors often produce electromagnetically induced noise. This high-pitch noise depends on the speed and torque level of the machine, as well as the motor type. [5] Variable-frequency drives use pulse-width modulation, which introduces additional current harmonics and results in higher acoustic noise. The switching frequency of ...
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