Hi,
the last few months I was testing different MEMS Microphones in breakout Boards in an ultrasonic surrounding (up to 120 kHz). I found that the frequencies could be measured correctly with several MEMS Microphones. However, the ultrasonic Signal is too strong at lower frequencies (around 25 kHz) so that the MEMS-Signal starts to clip (I used only analog MEMS).
I think the solution for this might be, to use a MEMS Microphone with an lower sensibility (around -50 dBV?).
The VM2020 Breakout Board you were offering seems perfect for me. Unfortunately this MEMS isn’t produced anymore. 
Do you have an similar Breakout Board or any MEMS you can suggest me?
I also found the MM20-33366-000 from Knowles, with specs that may fit my need. Unforntunately there are no breakout Boards for this MEMS.
Thank you!