| 摘要 |
PROBLEM TO BE SOLVED: To prevent an acoustic instrument from malfunctioning in points of temperature and humidity by partitioning a tube inside space into a first space facing to an instrument actuating part of the acoustic instrument and a second space communicated with and connected to a duct inside space, and arranging a partition layer having sound transmissivity, heat insulating performance and humidity impermeability in a deriving tube. SOLUTION: A deriving tube 4 is provided in a prescribed part of a duct 3, and a microphone M1 is arranged in a non-duct side end part of this deriving tube 4. A sound transmissive, heat insulating and moistureproof high polymer film 10 (this becomes a partition layer) is arranged in a deriving tube intermediate part in the positional relationship of cutting off a communicating condition of a detecting surface 8 (an instrument actuating part) of the microphone M1 and a duct inside space 9. Therefore, by this constitution, the duct inside space 9 and a space (a second space 11) of a deriving tube inlet part are put in a communicating condition, and a single closed space (a first space 12) is formed between the high polymer film 10 and the microphone detecting surface 8 separately from this space 11. A heat insulating effect by this space can be obtained by arranging this space. |
