The background to CEDAR DNS
"Whatever your dialogue noise suppression requirements, the answer is CEDAR DNS."
Noise is all around us: traffic, aircraft, the noise inside vehicles, air conditioning, wind, rain and other water noises, the noise from domestic appliances and even excessive reverberation. It annoys people, and it can render many recordings unusable. So noise suppression techniques are used 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 CEDAR's Academy Award winning DNS technology, you were forced to use 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 the filtering effect. Gates have no effect when the desired signal is present and lead to unnatural gaps in the signal. Other dynamics processes generate pumping, distortion and other unnatural effects, and encode/decode processes when used in this way simply act as dynamics processors. Even the digital noise reduction methods used in most dehissers and other broadband noise reduction systems are inadequate, generating unpleasant artefacts (known variously as 'twittering' and 'glugging') that can render the audio unuseable.
Furthermore, other digital noise reduction systems add a significant delay to the audio making real-time use impossible where lip-sync is an issue. In contrast, the audio delay through any of CEDAR's DNS products is less than 10 samples (0.2ms at 48kHz) which is far too short for any issues of this nature.
The original CEDAR DNS process overcame all of these problems and resulted in a string of awards when implemented in our hardware (the DNS1000 and its descendents) and software products (DNS One and its siblings). Today, a further development of the DNS algorithm is designed specifically for broadcast and live sound applications and this forms the core of the DNS 8D.