Question 6/12 - Analysis methods using complex measurement signals including their application for speech enhancement techniques and hands-free telephony
(Continuation of Questions 4/12 and 6/12)
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 needs 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.
During Study Period 1997-2004 test signals and analysis techniques for use in telephonometry have been collected. This work led to Recommendations P.501 and P.502 and their updates. A new Recommendation on the testing of speech enhancement devices P. 330 was released. Test signals and analysis techniques allow to evaluate many different parameters but still some are missing (e.g. assessment of background noise) and it is very likely that new signal processing methods show up which can not be covered adequately by the existing signals and 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.581, G.115
Question
The following items are to be considered within the study of the question, special consideration should be given 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 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?
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- 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?
Tasks
The work to be performed should cover the following tasks:
- Identify and improve/adapt existing objective speech quality testing procedures.
- Identify and study new testing methodologies for background noise transmission quality.
- 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.
The work will result in the revision of relevant P-Series Recommendations P.330, P.340, P.501, P.502, P.581. A new P-Series Recommendation P.OQN (objective quality number) will be created.
Relationships
Recommendations: P.310, P.311, P.313, P.79, G.161, G.168, G.169
Questions: 3/12, 4/12, 9/12 and 16/16, 18/16
Study Groups: SG 16
Standardisation bodies: ETSI STQ, TISPAN, TIA, IEEE
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