We can not turn our attention to the Power, USB, and Utterance Detection Microphone PCB

The part number on this component was not readable, but it location near the power interface may mean that it is either a Diode or PMOS FET

Vesper VA1200 - Analog Piezoelectric MEMS Voice Accelerometer. Bone Sensor - used for Utterance Detection

Light based Proximity Detector. Detects when the microphone is in the ear canal or in the charger