| 摘要 |
<p>PURPOSE:To accurately discriminate the attribute of a detection plate at any time by inputting a 2nd sound from a desired position of piping where a reference sound travels and detecting the 2nd sound at an optional position. CONSTITUTION:The valve 1 of the gas piping A is closed and the reference sound f is sent in by an external speaker from a downstream branch pipe 2 nearby the valve and picked up by a microphone from a branch pipe 3; and the phase and level are adjusted and the 2nd sound f' which is opposite in phase and equal in level is sent in through a branch pipe 4 adjoining to the branch pipe 3. The sound in the piping A are taken out by the microphone at a position M1 or M2 where the attribute of the piping system needs to be investigated and detected on an oscilloscope or with the ears. At this time, the reference sound f is detected at the position M1, but attenuated and not detected at the position M2. Consequently, it is found that the detection position M1 is in the piping system on the left side of the sending-in position of the sound f' and the position M2 is on the right piping system.</p> |
