| 摘要 |
PROBLEM TO BE SOLVED: To provide a noise reduction system capable of reducing hammering noise repeatedly generated.SOLUTION: The noise reduction system for reducing noise including hammering noise emitted from an MRI apparatus, being repeatedly generated, includes: error signal generation means 10 for generating an error signal e on the basis of the detected noise; estimation noise generation means 22 for generating an estimation noise signal d' indicating an estimation value of an acoustic pressure of the noise on the basis of the error signal e and a fist control signal z to cancel the noise; delay signal generation means 24 having a time delay property D corresponding to a time interval in which the hammering noise is generated, for generating a delay signal r from the estimation noise signal d'; a control filter 21 for generating a first control signal u from the delay signal r; and a speaker unit 30 including at least one pair of a first filter generating a second control signal from the first control signal u and a control speaker outputting a control sound by converting the second control signal into a sonic wave and including transmission means for transmitting the control sound.SELECTED DRAWING: Figure 1 |
