Voice Enhancement
Noise Suppression

Technologies  / Voice Enhancement   / Noise Suppression
About
Audio Examples
Applications
Integration
Technical Information

 

About
 

Noise Suppression technology reduces stationary and transient noises in single-channel speech signals, which increases the signal-to-noise ratio, improves speech intelligibility and reduces listening fatigue.

Alango Noise Suppression (NS) technology operates on a single channel signal. The input signal is divided into a number of frequency sub-bands. The special block estimates ambient noise and signal levels in each frequency sub-band and then passes or attenuates the sub-band signals according to instant signal-to-noise ratios. The output signal is then recombined from the processed sub-band signals. Musical noise and other artifacts are eliminated by a proprietary post-processing procedure. Alango NS technology is distinguished by its ability for fast and precise tracking of ambient noise levels while preserving very high output speech quality. This allows suppressing both stationary and transient noises such as passing cars.

Noise suppression mode (fixed or dynamic), amount of noise suppression and noise adaptation time are configurable parameters. In the fixed mode noise is always reduced (SNR improved) by a specified number of decibels. In the dynamic mode the aggressiveness of noise reduction depends on the noise level. In other words; the more noise that is present - the more it is reduced. This facilitates the cleaning of strong transient noises such as noise created by passing cars while preserving the highest speech quality in quiet environments.

Alango Noise Suppression technology includes some unique features such as tone suppression and tone preservation.

Tone suppression allows reducing strong periodic tonal noises. For example, 50/60Hz or RF interferences often cause buzz noise that can be attenuated.

Tone preservation allows keeping the dial tone, DTMF or other tonal signals that are not noises and must be preserved.

 
Audio Examples
 

This page is under construction. Audio examples can be found here: http://old.alango.com/technologies-ns.php

Applications
 

Mobile phones, Bluetooth headsets, hands-free kits, video/audio conferencing equipment, intercom systems and many others.

 
Integration
 

Alango Noise Suppression is seamlessly integrated with other Alango technologies into one Voice Communication Package (VCP). Besides noise suppression it includes acoustic echo cancellation, dynamic range compressor, automatic volume and equalization control, speech enhancement, (optional) adaptive dual microphone and several other functions.

 
Technical Information
 
  • Noise suppression up to -30 dB
  • Processing delay: < 30 ms (8 ms minimal)
  • Supported sampling rates: 8 kHz, 16 kHz, 24kHz, 32kHz
  • Noise adaptation time: 150 - 1500 ms (parameter)
  • Available on multiple DSP and MCU cores (please contact us for more information)
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