The separation between the ultra-low power voice detection and the ADC is becoming essential in various applications to minimize the always-on circuitry (with no need of manual activation).
Such a feature may be implemented either with analog microphones or with MEMS microphones.

The WhisperTrigger for analog microphones is a voice detection feature for analog MEMS or Electret Condenser microphones with an interrupt signal as output combining the best rate of voice detection with the fastest detection time.