Search results
Results from the WOW.Com Content Network
An ultrasonic examination. Ultrasound is sound with frequencies greater than 20 kilohertz. [1] This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound.
Sound waves propagating through a liquid at ultrasonic frequencies have wavelengths many times longer than the molecular dimensions or the bond length between atoms in the molecule. Therefore, the sound wave cannot directly affect the vibrational energy of the bond, and can therefore not directly increase the internal energy of a molecule.
Ultrasound energy, simply known as ultrasound, is a type of mechanical energy called sound characterized by vibrating or moving particles within a medium. Ultrasound is distinguished by vibrations with a frequency greater than 20,000 Hz, compared to audible sounds that humans typically hear with frequencies between 20 and 20,000 Hz.
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 environment. This interaction can be described as either a diffraction, interference or a reflection or a mix of the ...
Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz, the audio frequency range, elicit an auditory percept in humans. In air at atmospheric pressure, these represent sound waves with wavelengths of 17 meters (56 ft) to 1.7 centimeters (0.67 in). Sound waves above 20 kHz are known as ultrasound and are not audible to ...
Buzz pollination, or sonication, serves as an example of a behavioral response to specific frequencies of vibrations in plants.Some 20000 plants species, [7] including Dodecatheon and Heliamphora have evolved buzz pollination in which they release pollen from anthers only when vibrated at a certain frequency created exclusively by bee flight muscles.
Ultrasonic algae control is a commercial technology that has been claimed to control the blooming of cyanobacteria, algae, and biofouling in lakes, and reservoirs, by using pulsed ultrasound. [ 6 ] [ 7 ] The duration of such treatment is supposed to take up to several months, depending on the water volume and algae species.
Some animals have been thought to perceive the infrasonic waves going through the earth, caused by natural disasters, and to use these as an early warning. An example of this is the 2004 Indian Ocean earthquake and tsunami. Animals were reported to have fled the area hours before the actual tsunami hit the shores of Asia.