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Sound power or acoustic power is the rate at which sound energy is emitted, reflected, transmitted or received, per unit time. [1] It is defined [2] as "through a surface, the product of the sound pressure, and the component of the particle velocity, at a point on the surface in the direction normal to the surface, integrated over that surface."
The plasma arc heats the surrounding air causing it to expand. Varying the electrical signal that drives the plasma and connected to the output of an audio amplifier, the plasma size varies which in turn varies the expansion of the surrounding air creating sound waves. [1]
The fundamental Schumann resonance is at approximately 7.83 Hz, the frequency at which the wavelength equals the circumference of the Earth, and higher harmonics occur at 14.1, 20.3, 26.4, and 32.4 Hz, etc. Lightning strikes excite these resonances, causing the Earth–ionosphere cavity to "ring" like a bell, resulting in a peak in the noise ...
This is because VLF waves are reflected from the bottom of the ionosphere, while higher frequency shortwave signals are returned to Earth from higher layers in the ionosphere, the F1 and F2 layers, by a refraction process, and spend most of their journey in the ionosphere, so they are much more affected by ionization gradients and turbulence ...
Later in the 20th century the term noise music came to refer to works consisting primarily of noise-based sound. In more general usage, noise is any unwanted sound or signal . In this sense, even sounds that would be perceived as musically ordinary in another context become noise if they interfere with the reception of a message desired by the ...
According to Danish noise and music theorist Torben Sangild, one single definition of noise in music is not possible. Sangild instead provides three basic definitions of noise: a musical acoustics definition, a second communicative definition based on distortion or disturbance of a communicative signal, and a third definition based in subjectivity (what is noise to one person can be meaningful ...
Relationship of the atmosphere and ionosphere. The ionosphere (/ aɪ ˈ ɒ n ə ˌ s f ɪər /) [1] [2] is the ionized part of the upper atmosphere of Earth, from about 48 km (30 mi) to 965 km (600 mi) above sea level, [3] a region that includes the thermosphere and parts of the mesosphere and exosphere. The ionosphere is ionized by solar ...
The Earth–ionosphere waveguide [1] is the phenomenon in which certain radio waves can propagate in the space between the ground and the boundary of the ionosphere. Because the ionosphere contains charged particles, it can behave as a conductor. The earth operates as a ground plane, and the resulting cavity behaves as a large waveguide.