A method of determining rock properties engaged by a drill bit during drilling operations, the method comprising the steps of: deriving a plurality of acoustic characteristics from an acoustic sensor data signal, the plurality of acoustic characteristics including mean frequency, mean amplitude, normalized deviation of frequency, normalized deviation of amplitude, and apparent power, wherein the acoustic sensor data signal is derived from an acoustic signal recording and transmitting system (300, 320, 350) including an acoustic sensor (33, 301, 321, 351), the acoustic sensor (33, 301, 321, 351) positioned on one of the following: a drive shaft of a top drive of a top drive drill rig, 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 (33, 301, 321, 351) 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; and correlating the mean frequency, the mean amplitude, the normalized deviation of frequency, the normalized deviation of amplitude, and the apparent power with the same types of acoustic characteristics of a rock sample of known lithology type to identify, in real time, one or more of (i) lithology type, and (ii) one or more petrophysical properties of rock engaged by a drill bit during drilling operations, wherein correlating comprises: digitizing acoustic data contained within the acoustic sensor data signal, thereby to generate digitized acoustic data; transmitting the digitized acoustic data to a computer; transforming the digitized acoustic data into Fast Fourier Transform, FFT, data by a Fast Fourier Transformation; filtering the FFT data; and processing the filtered FFT data by an acoustic characteristics evaluation algorithm and/or petrophysical properties evaluation algorithm. deriving a plurality of acoustic characteristics from an acoustic sensor data signal, the plurality of acoustic characteristics including mean frequency, mean amplitude, normalized deviation of frequency, normalized deviation of amplitude, and apparent power, wherein the acoustic sensor data signal is derived from an acoustic signal recording and transmitting system (300, 320, 350) including an acoustic sensor (33, 301, 321, 351), the acoustic sensor (33, 301, 321, 351) positioned on one of the following: a drive shaft of a top drive of a top drive drill rig, 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 (33, 301, 321, 351) 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; and correlating the mean frequency, the mean amplitude, the normalized deviation of frequency, the normalized deviation of amplitude, and the apparent power with the same types of acoustic characteristics of a rock sample of known lithology type to identify, in real time, one or more of (i) lithology type, and (ii) one or more petrophysical properties of rock engaged by a drill bit during drilling operations, wherein correlating comprises: digitizing acoustic data contained within the acoustic sensor data signal, thereby to generate digitized acoustic data; transmitting the digitized acoustic data to a computer; transforming the digitized acoustic data into Fast Fourier Transform, FFT, data by a Fast Fourier Transformation; filtering the FFT data; and processing the filtered FFT data by an acoustic characteristics evaluation algorithm and/or petrophysical properties evaluation algorithm. digitizing acoustic data contained within the acoustic sensor data signal, thereby to generate digitized acoustic data; transmitting the digitized acoustic data to a computer; transforming the digitized acoustic data into Fast Fourier Transform, FFT, data by a Fast Fourier Transformation; filtering the FFT data; and processing the filtered FFT data by an acoustic characteristics evaluation algorithm and/or petrophysical properties evaluation algorithm.