PURPOSE: To mechanically estimate the pipe extension of a water pipe from a sound collection point to a water leake point, by measuring the power of the entire frequency band component of a water leak sound and that of the low frequency band component thereof.
CONSTITUTION: A water leak sound is collected by a mounted pickup 1 and a power measuring part 2 outputs the power signal P of the entire frequency band component of a water leak sound signal 7. A low-pass filter 3 extracts the low frequency band signal 8 containing only the low frequency band component of the water leak sound from the water leak sound signal 7 and a power measuring part 4 outputs the power signal PL of the low frequency band component of the water leak sound. Since both of a sound pressure level and a low band power ratio have the correlation with pipe extension (d), a pipe extension estimation part 6 estimates the pipe extension of a water pipe from the sound collection point to the water leak point from the values of the sound pressure level and the low band power ratio to display the same on a pipe extension display part 6.
MIZUKAMI TOSHIHIKO
SAKUMA MASARU
MURAYAMA EISHICHI
TOKYO METROPOLITAN GOV