1 Scope
2 References
3 Definitions
3.1 Terms defined elsewhere
3.2 Terms defined in this
Recommendation
4 Abbreviations and acronyms
5 Conventions
6 How to use this Recommendation
6.1 Determining compliance with this Recommendation
6.2 Testing at different stages of the development cycle
6.3 Application of this Recommendation to acoustic zoning concepts
7 Test arrangement
7.1 Test arrangement in a car
8 Test signals and test signal
levels
9 Measurement parameters and
requirements for hands-free terminals
9.1 Delay
9.2 Loudness ratings
9.3 Loudness
9.4 Sensitivity frequency responses
9.5 Listening speech quality during single talk
9.6 Listening speech
quality stability
9.7 Idle channel noise
9.8 Distortion in send
9.9 Distortion in receive
9.10 Echo performance
9.11 Switching characteristics
9.12 Double talk
performance
9.13 Background noise
transmission
10 Guidance on subjective testing
Annex A – Speech quality measurements
Annex B – Principles of Relative Approach
Annex C – Example for a questionnaire for subjective testing
C Performance rating
C.1 Overview
C.2 Test categories and rating types
C.3 Speech and background noise quality in send direction
C.4 Speech quality in receive direction (in the car under test)
C.5 Echo cancellation performance
C.6 Hands-free system stability tests (car-to-car)
Annex D – Standard set of user scenarios
Annex E – System stability with insufficient far‑end echo loss
Annex F – Microphone related sound field reproduction technique – multi-point
noise simulation (MPNS) method
F.1 Loudspeaker set-up in the car
F.2 Microphone set-up in the car
F.3 Background noise recordings and reference noise
F.4 Equalization
F.5 Accuracy of the
equalization
Bibliography