| 摘要 |
PROBLEM TO BE SOLVED: To provide a penetration testing machine capable of obtaining an accurate small-capacity acoustic signal in which a noise component is removed from an acoustic signal obtainable by a sound detecting means. SOLUTION: This penetration testing machine is provided with the sound detecting means 10 capable of detecting a sound which is propagated via a penetration rod 7 along with the penetration of the penetration rod 7 into ground; and the acoustic signal detected by the means 10 is transmitted to a signal processing part 12. The processing part 12 determines the feature amount of the acoustic signal and a statistic obtainable from the feature amount, sets a threshold value from the statistic, obtains a position (time) of the generation of the feature amount beyond the threshold value, and sets a section of a prescribed width in the position of the generation. A part corresponding to the section is extracted from the original acoustic signal. Thus, only a characteristic part of the acoustic signal can be extracted.
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