CAM2: DNS

The world standard for background noise suppression

The Problem

Noise is all around us: traffic, aircraft, the noise inside vehicles, air conditioning, wind, rain and other water noises, excessive reverberation, even the noise from domestic appliances. It annoys people, and it can render many recordings unusable. So noise suppression techniques are needed to clean up noisy dialogue for film production, suppress ambient noise for live TV and radio broadcasting, revitalise sound effects libraries, and enhance speech for forensic audio investigations.

Until recently, "Noise Suppression" meant using processes such as low-pass and other filters, noise gates, dynamics processes, or processes developed from analogue encode/decode noise reduction systems. These often proved inadequate. Filtering is not selective about what it removes, and there is no relationship between the input and filtering effect. Gates have no effect when the desired signal is present and lead to unnatural gaps in the signal. Other processes generate pumping, distortion, and other unnatural effects, and encode/decode processes, when used in this way, simply act as dynamics processors.

The Solution

So how can you remove the rumble, the hiss, the whistles, the broadband noise and the "shot" noise from contaminated sounds? The answer is... you use CEDAR's award-winning DNS process. This splits the signal into a large number of well-defined bands, and sophisticated digital filters then analyse each of these bands, suppressing the noise independently in each. The innovative design of this filter bank allows you to control the DNS process using relatively few controls, making it simple and quick to use in all situations.

If you work with film dialogue, the speed, flexibility, and ease of use of DNS provides solutions to audio problems that you could not previously solve. And, with eight, 96kHz channels of the DNS algorithm in a convenient, automated format, it cannot be bettered for multi-channel post-production in the film, video, and TV industries.

In the audio forensic laboratory, DNS is ideal for removing motor noise from small covert recorders, for eliminating electrical interference, and for helping to clean up recordings suffering from unfavourable acoustics and poor microphone locations.

The plaudits

In February 2005, the ©Academy of Motion Picture Arts and Sciences® honoured CEDAR's Senior Engineer, Dr Christopher Hicks, and CEDAR's Engineering Director, Mr Dave Betts, with a Technical Achievement Award for the design and implementation of the CEDAR DNS1000™. Already a studio standard for eliminating background noises such as traffic and air conditioning, the CEDAR DNS1000 hardware unit has also won SSAIRA and PAR Awards in 2000 and 2001, and was nominated for a TEC Award in 2001.