Evaluation of the Average DC Offset Values for Nine Small Digital Audio Recorders.

The average DC offset values of recordings produced on nine small digital audio recorders were evaluated to determine if they demonstrated characteristics meaningful for forensic audio authenticity examinations when submitted audio files are compared with test recordings made using exemplar digital recorders. Five audio formats (PCM WAV, ADPCM WAV, MP3, WMA, and DSS) were tested with no input, using the internal microphone(s), and with two Olympus external microphones. The average DC offset values were calculated using sound editing, digital analysis, and scientific computing programs. Based on the standard deviations of the DC offsets in these recordings, their wide variation and inconsistency probably preclude meaningful comparisons between one-minute submitted digital audio recordings and exemplars in authenticity examinations. [ABSTRACT FROM AUTHOR]