Patent ID: 8408359

Claim:
An acoustic attenuation method based on the acoustic ray deflection theory, comprises of providing a temperature gradient, in which the temperature on the outer surface of the wall of the chamber is lower than that of the interior of the chamber, between the interior and the exterior of the chamber through a low temperature refrigeration system fixed on the external surface of the pipe wall of a muffler; and deflecting the acoustic ray inside the muffler pipeline toward the external surface with the lower temperature resulting from the said temperature gradient according to Fermat principle, in allowance of more acoustic rays transmitting into an absorption sound structure inner-lined to the muffler in the form of oblique incidence, resulting in the increase of the incidence angle of the acoustic wave in glancing incidence, the increase of the sound-absorption coefficient for the said absorption sound structure, more effectively absorbing the noise inside the muffler pipeline, the reduction the amplitude in the stimulated acoustics normal vibration pattern within the muffler pipeline, the increase of the acoustic attenuation capability of the muffler, and the decrease of the radiated noise.