Smart sensors comprising one or more microelectromechanical systems (MEMS) sensors and a digital signal processor (DSP) in a sensor package are described. An exemplary smart sensor can comprise a MEMS acoustic sensor or microphone and a DSP housed in a package or enclosure comprising a substrate and a lid and a package substrate that defines a back cavity for the MEMS acoustic sensor or microphone. Provided implementations can also comprise a MEMS motion sensor housed in the package or enclosure. Embodiments of the subject disclosure can provide improved power management and battery life from a single charge by intelligently responding to trigger events or wake events while also providing an always on sensor that persistently detects the trigger events or wake events. In addition, various physical configurations of smart sensors and MEMS sensor or microphone packages are described.