| 摘要 |
PROBLEM TO BE SOLVED: To obtain a noise reducing duct for improving the reduction of noise by a noise reducing device. SOLUTION: A noise reducing type duct 10 for detecting noise by a microphone 30, generating control sound from a speaker 36 in accordance with the noise, and reducing the noise is provided in the air supply passage of an air conditioning and ventilating device. This duct 10 is formed with an inside duct 16 made of a foaming aluminium material and an outside duct 22 made of a damping steel plate provided on the outer part of the inside duct 16. Further, a sound absorbing chamber 24 is formed between the inside duct 16 and the outside duct 22. Further, a support member for supporting the microphone 30 on the outside duct 22 is formed with the damping steel plate. |
