A system for processor wake-up based on sensor data includes an audio buffer, an envelope buffer, and a processor. The audio buffer is configured to store a first data from a sensor. The first data is generated according to a first sampling rate. The envelope buffer is configured to store a second data, which is derived from the first data according to a second sampling rate, which is less than the first sampling rate. The processor is configured to wake up periodically from an idle state and read the second data from the envelope buffer. If the second data indicates an activity, the processor is configured to read the first data from the audio buffer. If the second data does not indicate an activity, the processor is configured to return to the idle state.