Methods of identifying rock properties in real-time during drilling, are provided. An example of method includes connecting a downhole sensor subassembly between a drill bit and a drill string, operably coupling acoustic sensors to a downhole processor, operably coupling a borehole telemetry system, downhole and surface data transmitting interfaces, and a surface computer to the downhole data transmitting interface. The method also includes receiving raw acoustic sensor data resulting from rotational contact of the drill bit with rock by the downhole processor, transforming the raw acoustic sensor data into the frequency domain, filtering the transformed data, and deriving acoustic characteristics from the filtered data. The method also includes the surface computer receiving the acoustic characteristics and deriving petrophysical properties from the acoustic characteristics directly or by utilizing a petrophysical properties evaluation algorithm.