| abstract |
Provided is an acoustic sensor that is efficient in adjusting a frequency range in which sound is collected and has high sound collection sensitivity. An acoustic sensor includes a cylindrical spacer, a vibration plate attached to the spacer so as to close one opening of the spacer, a back plate that closes the other opening of the spacer, and vibration. A vibration electrode film 27 provided on the back plate side of the plate 23, a back electrode film 28 provided on the vibration plate side of the back plate, and an electret film 29 are provided. In the diaphragm 23, a groove 24 that divides the diaphragm 23 into an inner region 23 i and an outer region 23 o is formed inside the inner surface of the cylindrical spacer 21. The electret film 29 is formed on the back electrode film side of the vibrating electrode film 27 and inside the groove 24. [Selection] Figure 1 |