Microphone sensor help, calibration and filter library help

Hi there i'm trying to implement a sync tester, this listens to audio blips using an electret mic (pre-amped) and then time it with a a light sensor.

Im not getting very useful information on PIN A0 (the mic input)

Its quite a small range with the test signal i'm using...

Im getting a signal level between 92mV and 242mV, measured with a DSO at the analog mic pin.

Im using a calibrator library

http://julianvidal.com/blog/calibrator-an-arduino-library-to-calibrate-sensors-hooked-to-analog-inputs/

Which doesn't really map the lows and highs like i would have thought.

Im also trying to use

https://github.com/jeroendoggen/Arduino-signal-filtering-library

But i'm getting "'SignalFilter' does not name a type" when I run the examples.

Any hints or thoughts would be great!