Well... Apple have introduced a default setting in their latest High Sierra OS

That actually tells the microphone to FILTER OUT BACKGROUND NOISE.... not great when we are trying to measure background noise!

The GOOD NEWS

is their is an easy fix. You just have to go into the Microphone settings and disable an option called 

"Use ambient Noise reduction"

COOL - SHOW ME THE FIX!

It's Fine take me to the app
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