Hey! I want to measure wind induced ambient noise levels in dB in forest habitats with AudioMoth to analyze the distribution of frequencies (I am mainly interested in the spectrum 500Hz - 4kHz). Do I need an external microphone, compatible with a common sound pressure calibrator (eg. 94dB at 1kHz) or is it possible to calibrate the built-in microphone, as well? What else do I have to consider?