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Deprecated - Noise Reduction Configurations

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Deprecated Content

This page refers to outdated, obsolete, or deprecated products or software. This is provided for historical reference for users of older releases. Please see our Current Asterisk Documentation.

The LumenVox Speech Engine features several configurationsin its handling of noise reduction.

Noise reduction is accomplished by taking a sample of thebackground noise in the audio being streamed to the Engine. As long as it’sdone at the beginning of the stream – before the caller starts speaking – theEngine can gauge how much of the noise after the caller has startedspeaking is just background noise. This computation takes less than a second.

This technology is particularly useful in noisyenvironments, such as a crowded place, or in a car.

Noise Reduction Settings

There are now 4 settings to use to counter noisy backgrounds. They are configured in the NOISE_REDUCTION_ENABLE parameter of your client_property.conf file.


Description: Disables all noise reduction. We do not recommend disabling all noise reduction, as the increased presence of background noise will also likely increase the time needed to decode speech. However, this may be used in debugging another system's noise reduction features, or examining the audio itself. 

Value: 0


Description: This is our default Noise Reduction algorithm, custom built for our Speech Engine and recommended for most of its applications. It is automatically activated when you install the Engine. 

Value: 1


Description: This is a new Noise Reduction model for the LumenVox Speech Engine. It works by filtering different types of noise than the Default model. There are no criteria for which one will work best in a given environment, but it is recommended that you start with the Default model. 

Value: 2


Description: This is another new model. It adapts to the noise signal, and continuously updates its noise estimation. This is particularly well suited to settings where the background noise will fluctuate, like the outdoors or a car. However, this model may not function as well in stationary noise environments, like a home or an office. 

Value: 3

In order to change your Noise Reduction model, you will needto modify your client_property.conf, which is located in /etc/lumenvox/.