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The hissing of high voltage transmission lines is due to corona discharge, not magnetism. The phenomenon is also called audible magnetic noise, [ 1 ] electromagnetic acoustic noise, lamination vibration [ 2 ] or electromagnetically induced acoustic noise, [ 3 ] or more rarely, electrical noise, [ 4 ] or "coil noise", depending on the application.
where is the sound frequency in hertz (Hz), is the speed of sound in air at 20°C in meters/second, and is the length of the transmission line in meters. The complex loading of the bass drive unit demands specific Thiele-Small driver parameters to realise the full benefits of a TL design. However, most drive units in the marketplace are ...
The name was given because the sound slowly decreases in frequency over about seven minutes. It was recorded using an autonomous hydrophone array. [8] The sound has been picked up several times each year since 1997. [9] One of the hypotheses on the origin of the sound is moving ice in Antarctica. Sound spectrograms of vibrations caused by ...
This falls within the domain of physical acoustics. In fluids, sound propagates primarily as a pressure wave. In solids, mechanical waves can take many forms including longitudinal waves, transverse waves and surface waves. Acoustics looks first at the pressure levels and frequencies in the sound wave and how the wave interacts with the ...
A sound attenuator, or duct silencer, sound trap, or muffler, is a noise control acoustical treatment of Heating Ventilating and Air-Conditioning (HVAC) ductwork designed to reduce transmission of noise through the ductwork, either from equipment into occupied spaces in a building, or between occupied spaces. [1] [2]
In acoustics, Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity.It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a rate α given by = where η is the dynamic viscosity coefficient of the fluid, ω is the sound's angular frequency, ρ is the fluid ...
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Specific acoustic impedance z is an intensive property of a particular medium (e.g., the z of air or water can be specified); on the other hand, acoustic impedance Z is an extensive property of a particular medium and geometry (e.g., the Z of a particular duct filled with air can be specified).