| 摘要 |
PURPOSE:To compare the sound pressure value of response sound with a judge reference value to judge the same even in a case low in response sound, by removing the continuous time part of a present collision sound in the time series waveform of the impact sound generated by striking a wall surface in definite kinetic quantity and caught by a sound receiver. CONSTITUTION:An impact sound transmitting and receiving part 1 is set to a wall surface W, and the delay time corresponding to the collision sound continuous time in such a case that a healthy concrete wall surface W having no cavity part S is struck and the judge reference value of the sound pressure corresponding to the upper limit value of the response sound pressure of the healthy part are inputted to a measurement controlling computer 10. Subsequently, a striking hammer 3 is operated to strike the wall surface W and the striking sound signal based on the striking sound received from a striking sound receiving part 8 by a microphone 5 is inputted and the measurement of the striking sound signal is delayed by a set delay time and the striking sound signal is measured by measure the sound pressure of the response sound. Next, it is judged whether the sound pressure of the response sound is a judge reference value or less and, when said sound pressure is the judge reference value or less, the struck part is judged to be a healthy part. When the sound pressure of the response sound is larger than the judge reference value, the presence of the cavity S is judged and concrete is moved by a predetermined distance to perform delay, measurement and judgement. |
