| 摘要 |
PURPOSE:To measure the actual condition of environmental noises accurately by interrupting the measurement of noises for the period when the sounds detected with a microphone put on the body are above the prescribed value. CONSTITUTION:After the noise signals collected with a microphone 11 are subjected to A characteristic amplification 12, the signals are subjected to square operation 13, and V/F conversion 14 to pulse trains. The pulse trains are counted with a counter 15 via a gate 17 and the integrated level of noises is digitally displayed as a noise exposure level. On the other hand, the sounds produced by the operator per se is detected with a small-sized microphone 18 put on his body, and is applied via an amplifier 19 and a rectifier circuit 20 to a comparator 21. When the sound pressure thereof rises above the value that affects the measurement of noises, the output of the circuit 21 inverts to close the gate 17 thereby interrupting the inputting to the counter 15. |
