STFbreadcrumb separatorSTFsbreadcrumb separatorSTF Homepagesbreadcrumb separatorT005

Testing Task Force T005:
Characterization of the New ETSI speech codec based on subjective Test data bases – CNET

Who we are:

STF Leader:    Joachim Pomy, Focus Infocom Gesellschaft für Informatik und Telekommunikation mbH,
STF Experts:    Jan Holub, s.r.o (Ltd.),
Markus Schnell, Fraunhofer Institut für Integrierte Schaltungen IIS,

What we do

The subjective and objective methodology for the characterization of the new ETSI speech codec has been developed in cooperation between TC STQ and TC DECT. It also specifies the performance requirements for this codec.
TS 103 624 which was developed in that respect provides information on the characterization methodology and requirements. It describes experimental tests and conditions to be tested. Additionally, objective evaluation to be applied is described.
The Low Complexity Communication Codec Plus (LC3plus) which was developed under the jurisdiction of TC DECT (TS 103 634) will be the new ETSI codec if it can be characterized according to the requirements specified in TS 103 624 with the intention to be able to standardize a high-quality codec for the use in modern telecommunication networks, including but not limited to DECT and VoIP. A special focus is paying tribute to the fact that end-to-end connections, i.e. from user to user, are in many cases of a hybrid nature concatenating different technologies and thus tandeming different codecs.

The work to be performed in this project is to create a set of high-quality recordings for the codec tandeming scenarios stipulated by TS 103 624 (test sequences) and conduct a statistically sufficiently large number of auditory tests (subjective tests).

There are 2 main tasks to be completed:
•    creation of a set of test sequences
•    conducting and analysing subjective tests.
For more details, see our  Terms of Reference

Why we do it

The candidate codec has been contributed in the DECT community and in order to give the markets also outside this community the certainty that this codec can be used with confidence in maintaining high speech quality under all circumstances or formal charachterization is necessary.

How we do it

Due to current situation, the TTF experts are working remotely from their locations (Germany, Czech Republic). The subjective tests will be performed in listening laboratory premises in Prague using native English and Mandarin speakers.


The following detailed information will be added to TS 103 624:
•    Characterization Methodology and Requirement Specifications for the ETSI LC3plus codec
•    Results from Characterization Testing of the ETSI LC3plus codec
After approval by ETSI STQ, the revised version(s) of TS 103 624 will be available to the general public.

Time plan

STQ approval is scheduled for end of September 2021.


How to contact us

If additional information is needed, please send an email to

This information is based upon STF working assumptions.

The views expressed do not necessarily represent the position of ETSI in this context.