Video or audio recording helps a criminal investigator to analyze the scene and to collect evidences. In this regards, a robust method is required to assure the originality of the recording. In this paper, we focus on the digital audio forensics and study how to extract the unique digital traces of any microphone. We perform feature extraction on the recording that is collected from several microphone models with at least two identical microphones of each model. Experimental results and analysis indicate that the signal of the sound recording of the identical microphone has different digital traces.