| 摘要 |
PURPOSE:To enable the measurement of a correct formation temperature even not in a special environment, by a method wherein the level of an extraneous noise is lowered with a sound absorbing material, cut with a level adjustor and a signal is discriminated with a variable band filter. CONSTITUTION:A mineral is heated with an electric furnace 4 and a decrepitation sound generated from a fluid wrapping object contained therein is caught with a microphone 9. In the measurement of such a type, a sound absorbing material 4 is provided about the electric furnace 4 to lower the level of the extraneous noise. The detection signal of the microphone 9 is passed through a level adjustor 21 adapted to select and output the waveform above a specified level by the microphone 9. In addition, a variable band filter 22 is used to discriminate a signal with the frequency band of the decrepitation. This allows the removal of extraneous noise in a double manner.
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