| 摘要 |
<p>Spaced rows of elements are disposed such as to form three passages extending between the rows. The spacing is such as to cause a phase lag in sound passing through of approx. 180 deg. in two of the passages. In the third passage, a 360 deg. phase lag is caused. In use, the noise reducing device is placed between the noise source and the place which is to be noise-controlled. The elements are spaced and positioned according to the frequency of noise to be controlled. Pref. the elements are aligned in columns to define ducts extending perpendicular to the passages.</p> |
