ABSTRACT
Digital audio editing software or waveform editors are the main tools used in audio forensics and enhancement. The history of audio forensics probably goes back to its use by the military as far back as World War II, when sound spectrographs were used to try to identify enemy voices in radio transmissions. The main goal of forensic audio enhancement is to make the spoken voices in a recording more discernible. Audio CDs use a sample rate of 44,100 Hz because the resulting Nyquist-Shannon frequency is 22,050 Hz—just above the 20,000 Hz limit of human hearing. The human voice has a random waveform, whereas the unwanted background noise in a recording can be a nonrandom repeating noise pattern. Analog and digital signal processing (DSP) hardware was used to process audio, to filter out background noise, and so on. Closed-back headphones are also useful in situations where the listener needs to prevent noise leakage.
