I could not find detailed spec's about the LM49155 extremely small IC made for cell phones. It has 36 tiny "bumps" on its bottom for a computerized robot to solder.
You said you have a microphone inside and another microphone outside. You subtract their signals to try to reduce "noise" but what noise will be the same to both microphones? Outside my home I hear noise from traffic, kids who are playing, dogs barking and ambulance sirens. None of these noises are heard inside my home. My home has low level noises from the furnace and TV playing that are not heard outside. Therefore I cannot use two subtracting microphones to reduce any of these noises.