| 摘要 |
PURPOSE:To enable the accurate measurement of low-frequency vibrations of the outside air even when there is a slight wind by a method wherein a microphone covered with a wind-breaking screen is set in a box having a gap through which a change in a static pressure of the outside air can be propagated into a space inside the box, and said low-frequency vibrations are measured by the microphone. CONSTITUTION:The junctions of a top face 15 and side faces 12, 13 and 14 of a wind-breaking box 11 are closely sealed by a gummed tape or the like, and a bottom face thereof is opened. The box 11 thus formed is set upward in a flat place when it is employed. This box is designed so that only the vibrations of the atmosphere and the outside air are propagated to the inside thereof through a gap between a setting plane and the lower-edge portion of each of the side faces 12, 13 and 14. A microphone 2, which is mounted on a tripod 17, covered with a wind-breaking screen 18 and housed in the wind-breaking box 11, is used as a sensor for measuring the low-frequency air vibrations of the outside air. By this constitution, the low-frequency air vibrations can be measured accurately even in the condition that there is a slight wind. |
