(Continuation of Question 20/12 and of part of Question 14/12)
The telecommunications industry is working to adopt more flexible
infrastructure to control costs and facilitate the introduction of new services.
Examples are next generation IP networks (NGN) and 3G mobile networks – both of
which exhibit time-varying performance. Measures that predict user-experience
are useful in monitoring and managing time-varying performance and help to
facilitate the rollout, efficient operation and effective service management of
The industry is already benefiting from ITU-T recommendations for objective
speech quality assessment. Most of the techniques described in these
recommendations are signal based and address listening only contexts. Signal
processing technology can be used to estimate the contribution of a number of
factors affecting the transmission performance of the complete connection.
The accuracy of such methods is high, but this requires a quantity of memory
and processing power that does not allow their application in all situations.
However, the current recommendations do not cover some important needs of the
The first need concerns conversational quality. Typical communications
involve interactive, two-way, conversations. IP and mobile networks can be
particularly deleterious to interactive applications, including voice
conversation; for example due to increased delay, which in turn will increase
the probability of double-talk and increase the perceptibility of echo.
There is therefore a need for a real-time, or near real-time, conversational
speech quality assessment method. Such a method would go much beyond the current
methods and could combine ‘conversational’ impairments, such as level, echo and
delay, together with ‘listening quality’ measures to provide an assessment of
the overall (conversational) quality perceived by the user at either end of the
connection. The development of such a method has started during the previous
study period under Q.20/12 and with the provisional name P.CQO.
It is envisaged that such a method would be developed collaboratively.
The second need is related to impairments of radio access. The most commonly
used service in mobile networks is still the circuit switched voice service.
There is no standard for a non intrusive speech quality model or conformance
test framework for normal circuit switched speech over a mobile radio
connection. The most dominant source of adverse speech quality for a circuit
switched speech call in a mobile network is the radio link in the transmission
path. Therefore it possible to make a pretty good estimation of perceived speech
quality based on radio transmission parameters and information about speech
codec and codec mode. A new study item is therefore required for non-intrusive
speech quality measurement with an objective model taking radio parameters as
input. The goal with the study would be to make a new recommendation with the
preliminary title “Conformance testing for circuit switched voice quality
The following Recommendations, in force at the time of approval of this
Question, fall under its responsibility:
P.56, P.561, P.562, P.564
Study items to be considered include, but are not limited to:
- What changes and/or improvements can be made to ITU-T Recommendations
P.561, P562 and P.564?
- How can non-intrusive measurements at the IP layers be implemented and
improved, for instance by taking into account new services or protocols or
transmission layers (e.g. RTCP XR)?
- What relationship exists between the subjective responses of users at the
terminals and the objective measurements made from the point at which the
non-intrusive assessment system is connected?
- What are the critical components of conversational speech quality?
- What measures give an estimate of the transmission quality of a connection
including the accumulated effects of all technologies (e.g. IP, wireless, ATM,
- How can such measures be used to assess, plan and maintain the transmission
quality of networks?
- What existing models and measures could be used as inputs to the new methods?
- What existing parametric or perceptual models, or components thereof, could be
used as building blocks for the new methods?
- What subjective test methods should method validation be based on?
- How can listening quality and conversational parameters be combined to assess
overall perception of conversational quality?
- What subjective test data is needed to develop the new methods?
- What additional considerations are relevant for wideband speech applications?
- How are non-intrusive measurements related to intrusive measurements?
- How can talking quality and conversational quality be measured in a
- Derivation of voice circuit-switched voice quality from non-intrusive radio
transmission parameter analysis
- Considerations on how to help measure and mitigate climate change.
Tasks include, but are not limited to:
- What changes and/or improvements can be made to ITU-T Recommendations P.561,
P.562 and P.564?
- Define the scope of P.CQO, which will combine multiple objective measurements
to provide an assessment of the perceived conversational speech quality in
- Review existing methods and models, and identify missing components
- Define inputs and outputs of P.CQO
- Identification of relevant subjective test methodologies (in co-operation with
- Identification of existing subjective test data
- Collection of new subjective test data
- Development of new Recommendation P.CQO on assessment of conversational speech
- Ensure consistency of P.CQO with development of P.OQN (Q.6/12).
An up-to-date status of work under this Question is contained in the SG 12 Work
Recommendations: P.340, P.56, P.561, P.562, P.563, P.564, P.800, P.800.1,
P.831, P.832, P.834, P.862, G.107, G.108, G.115, G.131
Questions: 2/12, 6/12, 7/12, 8/12, 9/12, 10/12, 11/12, 13/12, 14/12, 17/12
Study groups: ITU-T SG 2, SG 9, SG 16
Standardization bodies: ETSI (STQ, TISPAN), IETF (IPPM, AVT)