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Mechanical vibrations caused by charged cell membranes and walls is a leading hypothesis for acoustic emission generation. Myosins and other mechanochemical enzymes which use chemical energy in the form of ATP to produce mechanical vibrations in cells may also contribute to sound wave generation in plant cells. These mechanisms may lead to ...
Sound energy. In physics, sound energy is a form of energy that can be heard by living things. Only those waves that have a frequency of 16 Hz to 20 kHz are audible to humans. However, this range is an average and will slightly change from individual to individual. Sound waves that have frequencies below 16 Hz are called infrasonic and those ...
Sonochemistry. In chemistry, the study of sonochemistry is concerned with understanding the effect of ultrasound in forming acoustic cavitation in liquids, resulting in the initiation or enhancement of the chemical activity in the solution. [1] Therefore, the chemical effects of ultrasound do not come from a direct interaction of the ultrasonic ...
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. [1] [2] [3] The Doppler effect is named after the physicist Christian Doppler, who described the phenomenon in 1842. A common example of Doppler shift is the change of pitch heard when a ...
Acoustic emission is the transient elastic waves within a material, caused by the rapid release of localized stress energy. An event source is the phenomenon which releases elastic energy into the material, which then propagates as an elastic wave. Acoustic emissions can be detected in frequency ranges under 1 kHz, and have been reported at ...
A mysterious phenomenon first observed in 2013 aboard a vessel in a remote part of the Pacific Ocean appeared so preposterous, it convinced ocean scientist Andrew Sweetman that his monitoring ...
Beat (acoustics) In acoustics, a beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. With tuning instruments that can produce sustained tones, beats can be readily recognized.
Noise pollution, or sound pollution, is the propagation of noise or sound with ranging impacts on the activity of human or animal life, most of which are harmful to a degree. The source of outdoor noise worldwide is mainly caused by machines, transport and propagation systems. [1] [2] [3] Poor urban planning may give rise to noise ...