1. A method of analyzing properties of rock in a formation in real-time during drilling, the method comprising the steps of: receiving raw acoustic sensor data from one or more acoustic sensors by a downhole processor assembly, the one or more acoustic sensors carried by a downhole sensor subassembly positioned adjacent a drill bit and between a drill string and the drill bit, the downhole processor assembly positioned in close proximity to the one or more acoustic sensors and operably coupled thereto, the raw acoustic sensor data representing an acoustic signal generated real-time as a result of rotational contact of a drill bit with rock during drilling; and processing the raw acoustic sensor data by the downhole processor assembly, the step of processing including deriving a plurality of acoustic characteristics from the raw acoustic sensor data, the plurality of acoustics characteristics including mean frequency and normalized deviation of frequency.