Nuance Compatibility

IGEL Linux version 5.08.100 contains Nuance Citrix Client Audio Extension for Linux 7.47.0. The extension configures audio redirection on a Linux thin client in a Citrix environment, to provide optimal support for speech recognition.

Thin clients supported

Nuance supports the following IGEL thin clients with firmware version LX 5.08.100:

Audio devices supported


Sound card ID

Sound card name


Philips SpeechMike III


SpeechMike III


Philips SpeechMike Premium


SpeechMike III


Grundig Digta SonicMic II


Digta Sonic Mic II


Grundig Digta SonicMic II (US edition)


Digta SonicMic II US


Grundig Digta SonicMic 3


Digta SonicMic 3

Button controls are not supported with the firmware available at the release of Capture Services (Desktop) 5.0

For the selection of audio devices, the following priority conditions apply:

Audio formats

The following audio formats are supported:


Installing on an IGEL thin client (firmware version 5.08.100 or higher):

In version 5.08.100 and higher, the Nuance Citrix Client Audio Extension is delivered with the IGEL firmware. To activate the extension, do the following:

  1. Start the IGEL Setup utility.
  2. In the Sessions tab, browse for: Citrix XenDesktop / XenApp > HDX / ICA Global > Mapping > Device Support
  3. Enable Nuance Channel for Dictation.


To enable logging, do the following:

  1. Make sure that log4crc is available in the $HOME directory of the user who starts the client and rename it to .log4crc. For example:

    cp /usr/lib/ICAClient/log4crc /userhome/.log4crc

    Open .log4crc; if the file is read-only change it to read/write (you must have permissions to change the file).

  2. Set the priority to trace (for detailed logging) or error (for error logging only) and change the line which begins with category name = to:

    Audio extension: nuance.smac.citrix.sbext

    Mixer: nuance.smac.citrix.mixer

    If you do not want logging, comment out these lines or remove the .log4crc file completely.


Audio extension names are nca_ica_log.n and mixer nca_ica_mixer_log.n (where n is a consecutive number).

Philips SpeechMike

Button redirection: For Philips SpeechMike and Foot Control devices contact Philips Speech Processing Solutions. The Nuance Citrix Audio Extension does not provide support for SpeechMike button redirection.

SpeechMike (USB) audio: To use the Philips SpeechMike if it is not the default audio device, set the environment variable NUANCE_USED_SOUNDCARDNUMBER to the sound card number of the SpeechMike. If the environment variable does not exist or is invalid, the default sound card will be used.

Internal sound card

Recording with the internal sound card is not supported.

Using the internal sound card in parallel with a USB audio device is currently not possible because it is not possible to set the internal sound card as the default sound card when a USB default audio device is plugged in.