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Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface.Originally discovered for sound waves in the whispering gallery of St Paul's Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing, as well as in astronomy.
Portable magnetic-loop cave radios have been used by cavers for two-way communication and cave surveying since the 1960s. [1] In a typical setup the transmitting loop, consisting of many turns of copper wire, is oriented horizontally within the cave using a spirit level, and driven at a few kHz. Though such a small antenna is a very poor ...
German musician Daniel Rosenfeld had been making music under the moniker C418 since he was 15 years old, and was influenced by the electronic work of Aphex Twin. [1] From 2007, he became active on online indie game community TIGSource where he met Markus Persson, who was still in the early stages of developing Minecraft. [2]
The study of such sound waves is sometimes referred to as infrasonics, covering sounds beneath 20 Hz down to 0.1 Hz (and rarely to 0.001 Hz). People use this frequency range for monitoring earthquakes and volcanoes, charting rock and petroleum formations below the earth, and also in ballistocardiography and seismocardiography to study the ...
A cave survey is a map of all or part of a cave system, which may be produced to meet differing standards of accuracy depending on the cave conditions and equipment available underground. Cave surveying and cartography , i.e. the creation of an accurate, detailed map, is one of the most common technical activities undertaken within a cave and ...
Infrasound is sound waves with frequencies lower than 20 Hz. Although sounds of such low frequency are too low for humans to hear as a pitch, these sound are heard as discrete pulses (like the 'popping' sound of an idling motorcycle). Whales, elephants and other animals can detect infrasound and use it to communicate.
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 interference of two waves. In phase: the two lower waves combine (left panel), resulting in a wave of added amplitude (constructive interference). Out of phase: (here by 180 degrees), the two lower waves combine (right panel), resulting in a wave of zero amplitude (destructive interference). Interfering water waves on the surface of a lake