Basic research on sound waves

date：[2012-06-07] pk_hits：

After ultrasound acts on the medium, it produces a sound relaxation process in the medium. The sound relaxation process is accompanied by the transport of energy between the molecular charges, and at a macroscopic level, it exhibits absorption of sound waves (see sound waves). The characteristics and structure of substances can be explored through the absorption law of ultrasound by substances, which constitutes the acoustic branch of molecular acoustics. The wave length of ordinary sound waves is greater than the atomic spacing in solids, and under these conditions, solids can be considered as continuous media. But for ultrasonic waves with frequencies above 1012 Hz, the wavelength can be compared to the atomic spacing in the solid, and the solid must be treated as a lattice structure with spatial periodicity. The energy of lattice vibrations is quantized and called phonons (see solid-state physics). The effect of ultrasound on solids can be attributed to the interaction between ultrasound and thermal phonons, electrons, photons, and various quasi particles. The study of the generation, detection, and propagation laws of ultrasound in solids, as well as the study of acoustic phenomena in quantum liquid liquid helium, constitute a new field of modern acoustics.

Sound wave is one of the categories of sound, belonging to mechanical waves. Sound wave refers to a longitudinal wave that can be felt by the human ear, with a frequency range of 16Hz-20KHz. When the frequency of sound waves is below 20Hz, it is called infrasound waves, and above 20KHz, it is called ultrasonic sound waves.

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Basic research on sound waves