Some basic knowledge about acoustics

1, the sound waves
(1) the sound of three basic elements:
Frequency: the number of vibrations per second. The frequency of audible sound in 20-20 KHZ
Wavelength: the vibration of the sound source to complete a week, acoustic wave propagation distance. To hear the sound of wavelength in 17 m - 17 mm.
The spread of the sound velocity: every second. Sound velocity and temperature related, c = 331.4 + 0.6 t c m/s = f lambda
(2) spectrum: noise is usually made up of many frequency composite sound. Voice is different, its frequency and energy distribution of different. Because of this, can be the difference between a variety of sounds, sound frequency and energy distribution of these relations, called the sound spectrum, different sounds with different spectrum. For example, with frequency as the abscissa, sound pressure level as the ordinate, can make the sound of the sonogram.
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