| 摘要 |
PURPOSE:To effectively reduce production of noise by comparing environmental noise measured at plural prescribed locations and reducing either of the noises when the result of comparison indicates a specified or large level. CONSTITUTION:Only the noise generated by a cooling fan 35 is a noise source in the standby state and a microphone 2 is placed on a position P where office workers are usually resident. In this case, a CPU 36 stops the fan 35 once and allows the microphone 2 to measure the environmental noise in a state that no noise is generated from a main body 1. The output signal of the microphone is fetched and stored in a memory 38. Then the CPU 36 rotates the fan 35 to allow the microphone 2 to measure the environmental noise L1 at the location in the standby state and fetches the output signal and stores it in the memory 38. Then the CPU 36 compares the noise levels between L0, L1 stored in the memory 38 and calculates the difference to compare the calculated value with the standard noise DELTAL0 in a memory 37. When the calculated value is larger, the fan 35 is stopped to reduce the noise generated in the main body to reduce the environmental noise. |
