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Noise Reduction Products
DSP ALGORITHMS has developed a large family of noise reduction and speech enhancement
products suitable for most applications from speaker-phones to audio conferencing, and
from motorbike communication to Internet phones and car kits. Two categories of algorithms
can be recognized when it comes to speech enhancement. The first category uses multiple
microphones for recording (adaptive microphone arrays) while the second uses only a single
microphone, and therefore, can also be used to clean up existing recordings.
All algorithms are currently directly available for licensing for desktop as well as embedded
applications. Our consultancy department will be glad to help you in optimizing those products
for your specific applications and porting them to the hardware platform of your
choice. We will also be glad to help you identify the most effective product for your noise
problem, for this please email to
support@dspalgorithms.com.
The performance of a few single-microphone noise reduction algorithms is demonstrated below.
- BRIL, our latest developments in noise cancellers. Suitable for wide-band time-varying noise of arbitrary spectrum. Provides excellent noise reduction without affecting the speech.
- SANR135, designed specifically for reducing time-varying harmonic additive noise. Based on adaptive line enhancing algorithms.
- SANR145, suitable for wide-band time-varying noise of arbitrary spectrum. Based on improved spectral subtraction.
BRIL is a new proprietary algorithm has been recently developed for
adaptively estimating and removing background noise from speech signals. Unlike noise reduction and
speech enhancement algorithms currently available on the market, the new algorithm is capable of
cleaning noisy speech even in severe noisy environments without any distortion to the speech signal.
The algorithm has been successfully used in many communication systems with high level of
noise. BRIL is suitable for many applications such as car kits, mobile
telephony, conferencing, speech recognition, Internet phones, etc.
A Windows file processing demo is currently available. The demo package includes a Windows
file processing application, speech samples, and documentation. The Windows application takes an input
audio file (noisy speech) and allows you to adjust the algorithm parameters and writes the clean speech in an output
audio file. Request the BRIL noise canceller demo to test the algorithm
performance for your application. The performance of BRIL is demonstrated visually for different situations
in the figures below. You can listen to the audio associated with each image by clicking the "PLAY SAMPLE" link
below each image. Make sure to use good headphones for listening since most samples contain low
frequency noise that might not be well produced on small PC speakers.
The SANR135 is based on an adaptive line enhancer algorithm (harmonic noise reduction)
and therefore is very effective in reducing time-varying additive harmonic noise. Such
noise is usually superimposed on speech and audio signals from the recording hardware
and/or surrounding environment. Examples of this kind of noise are hum, hiss, computer
fan noise, etc. This algorithm is also suitable for multiple-tone siren noise usually
impairing the radio communication in ambulance and police vehicles. The adaptive
technique used by the SANR135 not only accurately estimates the noise but
can also track any changes in the noise frequency and amplitude. The effectiveness of the
SANR135 in reducing stationary as well as time-varying harmonic noise is demonstrated in
the samples below. You can listen to the audio associated with each image by clicking the "PLAY SAMPLE" link
below each image. Make sure to use good headphones for listening since most samples contain low
frequency noise that might not be well produced on small PC speakers.
A windows file processing demo is also available.
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| Stationary 4-harmonic noise before cleaning. PLAY SAMPLE |
Stationary 4-harmonic noise after cleaning. PLAY SAMPLE |
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| Variable frequency 4-harmonic noise before cleaning. PLAY SAMPLE |
Variable frequency 4-harmonic noise after cleaning. PLAY SAMPLE |
The SANR145 although based on the spectral subtraction principle, it
is absolutely free from musical noise and other problems usually found in products
based on this technique. The SANR145 is capable of reducing noise of arbitrary spectrum
including wide-band and harmonic noise. The tracking properties of SANR135 are, however,
superior to those of the SANR145 for harmonic noise reduction problems. The SANR145 in
recommended in reducing noise of arbitrary (stationary or slowly time-varying)
spectrum such as background noise, wind noise, quantization and coding noise, noise from the
communication channel, etc. The performance of the SANR145 is demonstrated in the
samples below. You can listen to the audio associated with each image by clicking the "PLAY SAMPLE" link
below each image. Make sure to use good headphones for listening since most samples contain low
frequency noise that might not be well produced on small PC speakers.
A windows file processing demo is also available.
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| Stationary wide-band noise before cleaning. PLAY SAMPLE |
Stationary wide-band noise after cleaning. PLAY SAMPLE |
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| Variable amplitude wide-band noise before cleaning. PLAY SAMPLE |
Variable amplitude wide-band noise after cleaning. PLAY SAMPLE |
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