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Shock wave. The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or ...
Sonic weapon. A long-range acoustic device ( LRAD) in use on the USS Blue Ridge. Sonic and ultrasonic weapons ( USW) are weapons of various types that use sound to injure or incapacitate an opponent. Some sonic weapons make a focused beam of sound or of ultrasound; others produce an area field of sound. As of 2023 military and police forces ...
Observers hear nothing until the shock wave, on the edges of the cone, crosses their location. Mach cone angle NASA data showing N-wave signature. [1] Conical shockwave with its hyperbola-shaped ground contact zone in yellow. A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed ...
A noise barrier (also called a soundwall, noise wall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect inhabitants of sensitive land use areas from noise pollution. Noise barriers are the most effective method of mitigating roadway, railway, and industrial noise sources – other than cessation of ...
A short-distance acoustic shadow occurs behind a building or a sound barrier. The sound from a source is shielded by the obstruction. Due to diffraction around the object, it will not be completely silent in the sound shadow. The amplitude of the sound can be reduced considerably, however, depending on the additional distance the sound has to ...
Electromagnetic interference ( EMI ), also called radio-frequency interference ( RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. [ 1] The disturbance may degrade the performance of the circuit or ...
Hazards. Dielectric heating from electromagnetic radiation can create a biological hazard. For example, touching or standing around an antenna while a high-power transmitter is in operation can cause burns. The mechanism is the same as that used in a microwave oven.
The pipe which held the "collector head" (microphone) can be seen in front of the structure. An acoustic mirror is a passive device used to reflect and focus (concentrate) sound waves. Parabolic acoustic mirrors are widely used in parabolic microphones to pick up sound from great distances, employed in surveillance and reporting of outdoor ...