Audio Enhancement Samples

Here are several audio demonstration (.mp3) files that highlight typical noise problems encountered in the law enforcement surveillance environment. These tracks include both real-life examples submitted by DAC customers and studio-generated examples created in the DAC laboratory. The studio examples offer a controlled environment to demonstrate the specific capabilities of DAC filter products in attacking common noise problems such as AC hum, compressor sounds, and 2-channel reference cancellation. The real-life examples demonstrate the DAC filter capabilities working against noise problems in an uncontrolled environment such as broadband noise, equipment interference, and near-far party imbalances. All examples were processed using commercially available equipment manufactured by Digital Audio Corporation.

SPECIAL NOTE: Please note that the primary objective of forensic noise cancellation is speech intelligibility, not fidelity. As such, while some examples may sound slightly distorted or the quality of the recording degraded after processing, the target speech may be more discernible. The files have been stored as “.mp3” files to minimize download time but their quality may be affected by this lossy compression.

Studio-Generated Demo Recordings

Before Processing		After Processing
60 Hz hum masking voice with audio		60 hz hum attenuated so voice is audible
Compressor noise masking quieter voice		Compressor noise attenuated so quieter speech is understandable.
Reverberation makes voice unintelligible		Reverberation is reduced so voice is intelligible.

Real-World Demo Recordings

Before Processing		After Processing
"Murder for Hire" sting operation. Muffled voice makes speech hard to understand.		Speech clearer and conversation intelligible.
Police station interview. Reverberation and 60 Hz Hum mask speech.		Speech is clearer as reverberation is reduced and hum removed.
Concealed microphone in light fixture. Speech level too quiet and 60 Hz Hum masks speech.		Voice level amplified and hum removed.
Microcassette recording in a night club. Music masks speech.		Music attenuated and speech more intelligible.
Conversation masked by music radio interference.		Music attenuated and speech clearer. (Noise reference separately recorded and used for cancellation)

".mp3" files are each approximately 400k in size and may take several minutes to completely download via a standard 56k modem connection.