| 摘要 |
The screen 1 forms a type of wall of considerable thickness, of the order of 10 cm, which is suitably cemented onto the ground, with the special feature that it has a great many transverse holes 6 which open both towards its face 2 which receives the incident wave 3 and also towards its face 4 via which the transmitted waves 5 emerge, in such a manner that these holes 6, with any section of small size, largely cancel out the frequencies which make up the incident wave 3, giving rise to a reduction in the energy transported by the wave which is greatly superior to that generated through the effect of absorption or simple reflection. The section of the holes 6 can be varied as a function of aesthetic or manufacturing conditions, since it does not affect the functional nature of the screen. <IMAGE>
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