Motivation

Terminal and network equipment increasingly includes complex signal processing techniques; wideband systems are entering the market place. Most devices can no longer be regarded as linear, time-invariant systems. The subjectively relevant transmission characteristics of such equipment need to be correctly determined using adequate measurement methods. There is a need of having reproducible, well defined measurement methods available -for certification labs as well as for developers which ideally should be combined to one quality value.

Test signals and analysis techniques for use in telephonometry have been collected in previous study periods. This work led to Recommendations P.330, P.501 and P.502, P.505 and their updates. Test signals and analysis techniques allow to evaluate many different parameters however they are mostly related to narrowband communication wideband up to fullband test procedures are missing; existing methods and signals need to be adapted since they may no longer be appropriate for new signal processing methods. In addition the interaction of signal processing at various locations of a connection needs to be investigated more in detail.

The evaluation methodologies for speech enhancing devices are still incomplete and need further improvement, new hands-free technologies require the adaptation of existing testing methodologies and the study of new procedures. There is a need to produce new product-oriented Recommendations including hands-free functions as, mobile, IP, conferencing and audiovisual terminals.

The following major Recommendations, in force at the time of approval of this Question, fall under its responsibility:

P.50, P.59, P.82, P.330, P.340, P.501, P.502, P.505, P.581, G.115

Question

The following items are to be considered within the study of the Question, special consideration should be given wideband/fullband systems, to VoIP terminals and signal processing used in VoIP:

• What kind of new complex signal processing used in terminals and networks may influence the speech transmission quality and what objective testing methodology can be used?
• What type of test signals and testing techniques are needed for wideband and fullband transmission systems?
• What test signals and test setups can be used to simulate noisy environments adequately?
• What methods are suitable for the objective assessment of background noise transmission and to what extent can the background noise transmission be assessed without making reference to the background noise signal?
• What testing methods/signals can be used to optimize background noise transmission in combination with VAD and comfort noise insertion techniques?
• What testing methods are needed for speech enhancement devices and what are the limits for the different quality determining parameters identified?
• What are the consequences on the speech quality of the combination of speech processing devices implemented in hands-free terminals? What characteristics and limits can apply for these combinations?
• What are the implications of the interaction between terminal signal processing and network signal processing on speech quality?
• How progresses in psycho-acoustic models could be applicable to HATS for the benefit of hands-free terminals testing?
• How can existing and/or new speech quality parameters be combined to a single speech quality representation covering all conversational aspects?
• Considerations on how to help measure and mitigate climate change.

Tasks

The work to be performed should cover the following tasks:

• Improve/adapt existing test signals and objective speech quality testing procedures.
• Identify and study new testing methodologies for wideband, superwidband and fullband systems
• Identify and study new testing methodologies for background noise transmission quality.
• Adapt/define a testing setup to simulate background noise scenarios in a lab environment.
• Evaluate existing and new methods for wideband transmission systems.
• Improve testing methods for speech enhancement devices and identify suitable limits for the different quality parameters.
• Add new testing methodologies, improve the existing testing techniques for modern hands-free terminals.
• Study the consequences on the speech quality of the combination of speech processing devices implemented in terminals and networks.
• Study applications to multichannel sound pick up (arrays) and multi channel/Multi device sound reproduction (incl. spatialisation, stereo) and the use of HATS in such situations.
• Study specific test methodologies applicable for hand-held, wearable, lap-top and conference hands-free terminals, and based on the real use context including audiovisual terminals.
•  Study and define a methodology for a representation of the overall speech quality for non linear and time variant communication systems taking into account the complete conversational situation.
   

An up-to-date status of work under this Question is contained in the SG 12 Work Programme http://www.itu.int/ITU-T/workprog/wp_search.aspx?isn_sp=545&isn_sg=551

Relationships

Recommendations: P.310, P.311, P.313, P.79, G.161, G.168, G.169, P.Carhft

Questions: 3/12, 4/12, 5/12, 9/12

Study Groups: ITU-T SG 16

Standardization bodies: ETSI STQ, TISPAN, 3GPP, 3GPP2, TIA, IEEE