The internal circuit board was also attached a MEMS Microphone that appeared to be monitoring the Speaker Chamber of the Headphone, since it was faced in

I had to remove the outside panel with 'R' on it with a Razor Knife to free the MEMS Microphone. Once the MEMS Microphone was freed, the interface board circuit could be pulled out

USB and Power (Charger) Interface

Sound Ports

Internal Circuit Board that interface Power and USB to the Headphones

MEMS Microphone from plastic collar in the Headphone

MEMS Microphone separated from the Interface Circuit Board when removed from the side of the Speaker Chamber