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Acousto-optics is a branch of physics that studies the interactions between sound waves and light waves, especially the diffraction of laser light by ultrasound (or sound in general) through an ultrasonic grating. A diffraction image showing the acousto-optic effect.
Diffraction is the same physical effect as interference, but interference is typically applied to superposition of a few waves and the term diffraction is used when many waves are superposed. [1]: 433 Italian scientist Francesco Maria Grimaldi coined the word diffraction and was the first to record accurate observations of the phenomenon in 1660.
The architectural details of a room influences the behaviour of sound waves within it, with the effects varying by frequency. Acoustic reflection , diffraction , and diffusion can combine to create audible phenomena such as room modes and standing waves at specific frequencies and locations, echos , and unique reverberation patterns.
A consequence of this is the frequency of the diffracted beam f in order m will be Doppler-shifted by an amount equal to the frequency of the sound wave F. + This frequency shift can be also understood by the fact that energy and momentum (of the photons and phonons) are conserved in the scattering process. A typical frequency shift varies from ...
Diffusion, in architectural acoustics, is the spreading of sound energy evenly in a given environment. A perfectly diffusive sound space is one in which the reverberation time is the same at any listening position. Most interior spaces are non-diffusive; the reverberation time is considerably different around the room.
A parametric array is a nonlinear transduction mechanism that generates narrow, nearly side lobe-free beams of low frequency sound, through the mixing and interaction of high-frequency sound waves. Applications are e.g. in underwater acoustics and audio.
Extremely high frequency (EHF) is the International Telecommunication Union designation for the band of radio frequencies in the electromagnetic spectrum from 30 to 300 gigahertz (GHz). [ 1 ] [ 2 ] It is in the microwave part of the radio spectrum, between the super high frequency band and the terahertz band .
The main cause of sound attenuation in fresh water, and at high frequency in sea water (above 100 kHz) is viscosity. Important additional contributions at lower frequency in seawater are associated with the ionic relaxation of boric acid (up to c. 10 kHz) [ 7 ] and magnesium sulfate (c. 10 kHz-100 kHz).