A method of identifying rock properties in real-time during drilling using a top drive drill rig comprising a top drive with a drive shaft, the method comprising the steps of: providing an acoustic signal recording and transmitting system (300, 320, 350) including an acoustic sensor (33, 301, 321, 351); positioning the acoustic sensor (33, 301, 321, 351) on one of the following: the drive shaft and an extension of the drive shaft of the top drive drill rig, the drive shaft including a plurality of extensions, wherein the extension of the drive shaft on which the acoustic sensor is positioned is a packing box which rotates with the drive shaft, an upper bearing cup positioned adjacent the packing box and stationary with respect to the drive shaft, or a rotary manifold operably coupled to and encircling a portion of the drive shaft, and wherein the drive shaft is connected to a drill string with a drill bit connected to the downhole end of the drill string; operably coupling a computer to one or more components of the acoustic signal recording and transmitting system (300, 320, 350) to establish communications therebetween; receiving an acoustic sensor data signal from the acoustic signal recording and transmitting system (300, 320, 350) by the computer, the acoustic sensor data signal representing an acoustic signal generated real-time by the acoustic sensor (33, 301, 321, 351) as a result of rotational contact of the drill bit with rock during drilling; and analyzing the acoustic sensor data signal by the computer to determine, real-time, at least one of the following: lithology type and one or more petrophysical properties of rock engaged by the drill bit during drilling operations. providing an acoustic signal recording and transmitting system (300, 320, 350) including an acoustic sensor (33, 301, 321, 351); positioning the acoustic sensor (33, 301, 321, 351) on one of the following: the drive shaft and an extension of the drive shaft of the top drive drill rig, the drive shaft including a plurality of extensions, wherein the extension of the drive shaft on which the acoustic sensor is positioned is a packing box which rotates with the drive shaft, an upper bearing cup positioned adjacent the packing box and stationary with respect to the drive shaft, or a rotary manifold operably coupled to and encircling a portion of the drive shaft, and wherein the drive shaft is connected to a drill string with a drill bit connected to the downhole end of the drill string; operably coupling a computer to one or more components of the acoustic signal recording and transmitting system (300, 320, 350) to establish communications therebetween; receiving an acoustic sensor data signal from the acoustic signal recording and transmitting system (300, 320, 350) by the computer, the acoustic sensor data signal representing an acoustic signal generated real-time by the acoustic sensor (33, 301, 321, 351) as a result of rotational contact of the drill bit with rock during drilling; and analyzing the acoustic sensor data signal by the computer to determine, real-time, at least one of the following: lithology type and one or more petrophysical properties of rock engaged by the drill bit during drilling operations.