Noise Reduction
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Noise Reduction

Last Updated: March 22, 2012

Noise Reduction (NR) is a voice enhancement process that improves the quality of incoming speech that has already been corrupted with background noise; for example, a voice conference participant speaking on a cell-phone in a car. NR works best with steady state broadband noises like engine noise but not as well with impulsive noises like nearby chatter.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Prerequisites for Noise Reduction

Cisco Unified Border Element

  • Cisco IOS Release 15.2(2)T, or a later release must be installed and running on your Cisco Unified Border Element.

  • Cisco IOS XE Release 3.6S or a later release must be installed and running on your Cisco ASR 1000 Series Router.

Restrictions for NR

  • Supported only on PVDM3.

  • Supported only on flex codec complexity.

  • No support for H.32x video call, complex forking calls, and fax and modem calls.

  • No support for Time-Division Multiplexing (TDM) hairpin call.

  • Configurations under POTS dial peer has higher priority over VoIP dial peer for NR.

  • Configurations under the dial peer has higher priority than configurations at the global level.

  • No support for conference calls, IP/SIP phones, and the Skinny Client Control Protocol (SCCP).

  • CLI supports enabling NR but not disabling NR.

  • No support for dynamically enabling or disabling NR during a call.

Information About NR

Noise Reduction

Noise Reduction (NR) is an adaptive signal processing algorithm on the Digital Signal Processor (DSP) that analyzes incoming audio, extracts a fingerprint of the background noise during talker pauses, and then performs ongoing spectral subtraction of this noise after a short training period (a few seconds). NR constantly adapts to changes in background noises over time.

NR can affect music on hold signals by making the music quieter. NR may disrupt fax/modem/TDD devices, although it is designed to self-disable in those cases. Use modem-relay mode for reliable fax/modem transmission. NR is supported on TDM gateways (TDM-VoIP and TDM-TDM) and on the Cisco Unified Border Element (Cisco UBE).

Some of the best practices for NR are as follows:

  • Use default values.
  • Do not use NR on dial peers associated with fax machines. Use fax or modem-relay modes for those dial peers.
  • NR, when used without dynamic user control of intensity (as is the case with gateways), must be used at a low intensity (default or lower) since it is always on. High intensity is dramatic for demonstrations with loud background noises, but the NR process itself will degrade "normal" calls if NR is run at high intensity.

How to Configure NR

Last Updated: March 22, 2012

Creating the Media Profile for NR

Perform this task to create a media profile to configure noise reduction parameters.

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   media profile nr tag

4.   intensity level

5.   noisefloor level

6.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
media profile nr tag


Example:

Device(config)# media profile nr 2

 

Creates the media profile to configure noise reduction parameters and enters media profile configuration mode. The range for the media profile tag is from 1 to 10000.

 
Step 4
intensity level


Example:

Device(cfg-mediaprofile)# intensity 2

 

Configures the intensity level or depth of the noise reduction process. The range is from 0 to 6.

 
Step 5
noisefloor level


Example:

Device(cfg-mediaprofile)# noisefloor -50

 

Configures the noise level, in dBm, above which NR will operate. NR will allow noises quieter than this level to pass without processing. The range is from -58 to -20.

 
Step 6
end


Example:

Device(config)# end

 

Returns to the privileged EXEC mode.

 

Creating the Media Class to Enable NR

After the media profile is created, you must create a media class to enable noise reduction. Perform this task to create a media class.

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   media class tag

4.   nr profile tag

5.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
media class tag


Example:

Device(config)# media class 2

 

Creates the media class to enable the noise reduction feature and enters media class configuration mode. The range for the media class tag is from 1 to 10000.

 
Step 4
nr profile tag


Example:

Device(cfg-mediaclass)# nr profile 200

 

Applies the media profile to the media class. The range for the media profile NR tag is from 1 to 10000.

 
Step 5
end


Example:

Device(config)# end

 

Returns to privileged EXEC mode.

 

Configuring the Media Class at a Dial Peer Level for NR

Perform this task to configure the media class for a dial peer.

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   dial-peer voice tag pots

4.   media-class tag

5.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
dial-peer voice tag pots


Example:

Device(config)# dial-peer voice 20 pots

 

Defines a particular dial peer and enters the dial-peer voice configuration mode. The range for the dial-peer voice tag is from 1 to 1073741823.

 
Step 4
media-class tag


Example:

Device(config-dial-peer)# media-class 2

 

Applies the media class to the specific dial peer. The range for the media class tag number is from 1 to 10000.

 
Step 5
end


Example:

Device(config-dial-peer)# end

 

Returns to the privileged EXEC mode.

 

Configuring the Media Class Globally for NR

Perform this task to configure a media class globally.

SUMMARY STEPS

1.    enable

2.   configure terminal

3.   media service

4.   enhancement

5.   tdm tag

6.   end


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
media service


Example:

Device(config)# media service

 

Enters media service configuration mode.

 
Step 4
enhancement


Example:

Device(cfg-mediaservice)# enhancement

 

Enters the submode enhance of media service.

 
Step 5
tdm tag


Example:

Device(cfg-service-enhance)# tdm 2

 

Applies the TDM call globally. The range for the media class tag number is from 1 to 10000.

 
Step 6
end


Example:

Device(config-dial-peer)# end

 

Returns to the privileged EXEC mode.

 

Verifying NR

Perform this task to verify the voice quality metrics.

SUMMARY STEPS

1.   enable

2.   show call active voice stats | b pid:


DETAILED STEPS
Step 1   enable


Example: 
Device> enable

Enables privileged EXEC mode.

Step 2   show call active voice stats | b pid:


Example: 
Device# show call active voice stats | b pid:1300

11EC : 5 09:14:25.971 PDT Thu Jul 28 2011.1 +1130 pid:1300 Answer 1300 active dur 00:01:36 tx:17/321 rx:17/321 dscp:0 media:0
DSP/TX: PK=17, SG=0, NS=1, DU=90570, VO=320
DSP/RX: PK=17, SG=0, CF=1, RX=90570, VO=320, BS=0, BP=0, LP=0, EP=0
….
DSP/DL: RT=0, ED=0
MIC Direction:
DSP/NR: NR=1, ND=0, LV=257, IN=1, PN=0, ON=0
DSP/AS: AE=1, AD=0, AV=0, AM=0, NT=0, DT=0, TT=0, TD=0, LF=0, LD=0
EAR Direction:
DSP/NR: NR=0, ND=0, LV=0, IN=0, PN=0, ON=0
DSP/AS: AE=0, AD=0, AV=0, AM=0, NT=0, DT=0, TT=0, TD=0, LF=0, LD=0
11EC : 6 09:14:25.973 PDT Thu Jul 28 2011.2 +1130 pid:2300 Originate 2300 active dur 00:01:36 tx:17/457 rx:17/321 dscp:0 media:0
Telephony call-legs: 1
SIP call-legs: 0
H323 call-legs: 1

Displays information about digital signal processing (DSP) voice quality metrics.

Troubleshooting Tips

The following commands can help troubleshoot NR:

  • debug voip hpi all
  • debug voip dsmp all
  • debug voip dsm all
  • debug voip vtsp all
  • debug vpm dsp all

Configuration Examples for the NR feature

Last Updated: March 22, 2012

Example: Enabling NR globally 

media profile nr 1
 intensity 1
! 
media profile nr 2
! 
media profile nr 3
 intensity 2
!
media profile nr 4
 intensity 3
!
media profile nr 5
 intensity 2
! 
media profile nr 7
 intensity 2
! 
media profile asp 6
! 
media class 1
 nr profile 5
 asp profile 6
! 
media service
 enhancement
  tdm 1

Example: Enabling NR on a Dial Peer 

media profile nr 1
 intensity 1
!
media profile nr 2
 intensity 2
!
media profile nr 3
 intensity 2
!
media profile asp 4
!
media class 1
 nr profile 2
 asp profile 4
!
dial-peer voice 2100 pots
 destination-pattern 2100
 incoming called-number 1100
 media-class 1
 port 0/2/0:1
 forward-digits all

dial-peer voice 1300 voip
 destination-pattern 1300
 session target ipv4:1.2.146.102
 media-class 1

Feature Information for Noise Reduction

Last Updated: March 22, 2012

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.

Table 1Feature Information for Noise Reduction
Feature Name Releases Feature Information

Noise Reduction

15.2(2)T,

15.2(3)T

Noise Reduction (NR) is a voice enhancement or restoration process that improves the quality of incoming speech that has already been corrupted with background noise. NR is supported on TDM gateways and on the Cisco UBE.

The following commands were introduced or modified: intensity, media profile nr, media service, and noisefloor.

Noise Reduction

Cisco IOS XE Release 3.6S

Noise Reduction (NR) is a voice enhancement or restoration process that improves the quality of incoming speech that has already been corrupted with background noise. NR is supported on TDM gateways and on Cisco UBE.

In Cisco IOS XE Release 3.6S, this feature was implemented on the Cisco Unified Border Element (Enterprise).

The following commands were introduced or modified: intensity, media profile nr, media service, noisefloor.

Last Updated: March 22, 2012

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

© 2012 Cisco Systems, Inc. All rights reserved.