| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an active silencer for an air blowing apparatus formed such that the degree of deterioration of a noise absorbing material and an acoustic generator is arbitrarily inspected. SOLUTION: A memory circuit 1 is provided to store a signal detected by a noise detector 105 when an air blowing apparatus 101 is operated in an initial state that a sound absorbing material 103 is not deteriorated. A signal detected by the noise detector 105 and a signal storing the initial state are compared with each other for computation by a computing circuit 2, and a display apparatus 3 is provided to display a difference obtained resultant from the comparison and computation. An inspector inspects the degree of deterioration of the sound absorbing material 103 only by reading display of the display apparatus. Thus, a need to visually inspect the internal part of a duct after a stop of the air blowing apparatus for a long period is eliminated and an exchange timing is decided without needing considerable cost and time.</p> |
