mems microphone:attenuate sound input

Question

mems microphone: I am looking for a mems microphone able to capture a sound pressure of 140 dB SPL. Apparently the maximum pressure an analog device microphone can withstand is 120 dB SPL. Is there a way to attenuate the sound before it goes into the microphone?

ADIApproved · Accepted Answer

You could put either an acoustic resistance or compliance in front of the microphone to attenuate the level of the sound incident at the microphone. The mic is a capacitive device, so a capacitive divider (a compliance) might give you the best response over the whole audio bandwidth. A compliance could be implemented with a stiff membrane over a cavity in front of the microphone, similar to what's shown in application note AN-1124 . Compared to what's described in that application note, though, you may want a thicker membrane. The purpose of the design described there is not to have much attenuation of the signal, as you're looking to do. 
 An acoustic resistance may be simpler to implement, just with a resistive mesh in front of the microphone's sound port. You can find acoustic meshes like this from suppliers like Saati. The downside of an implementation like this is that you may not see as flat of a response from the acoustic filter and may see a roll-off in the response at high frequencies.)

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mems microphone:attenuate sound input