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
7 Test arrangement
7.1 Test arrangement in a car
8 Digital interfaces for development, debugging and test
8.1 Interfaces and access points
8.2 Test set-up and tests
9 Test signals and test signal levels
9.1 Signals
9.2 Background noise signals
10 Measurement parameters and requirements for microphones used in
speakerphone hands-free systems
10.1 Microphone measurements in anechoic conditions
10.2 Microphone measurements in the car
11 Measurement parameters and requirements for hands-free terminals
11.1 Preparation measurements
11.2 Delay
11.3 Loudness ratings
11.4 Sensitivity frequency responses
11.5 Speech quality during single talk
11.6 Listening speech quality stability
11.7 Idle channel noise
11.8 Out-of-band signals
11.9 Distortion in send
11.10 Distortion in receive
11.11 Echo performance
11.12 Double talk performance
11.13 Background noise transmission
12 Verification of the transmission performance of short-range wireless
transmission enabled phones
12.1 Interface definition and calibration
12.2 SRW loudness ratings
12.3 SRW sensitivity frequency responses
12.4 SRW noise cancellation test in send direction
12.5 SRW speech quality during single talk
13 Car-to-car communication
14 Guidance on subjective testing
15 Corded headsets
15.1 Connector type
15.2 Connector wiring and electrical specifications
15.3 Headset receive characteristics
15.4 Headset transmit characteristics
15.5 Standard behaviour in the presence of corded headsets
16 Wireless headsets
16.1 Wireless headset types
16.2 Test methodology for verification of standard behaviour
16.3 Standard behaviour in the presence of wireless headsets
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 method (MPNS)
F.1 Loudspeaker setup in the car
F.2 Microphone setup in the car
F.3 Background noise recordings and reference noise
F.4 Equalization
F.5 Accuracy of the equalization
Appendix I – A method to determine the listening speech quality
I.1 One‑way speech quality in sending
I.2 One-way speech quality in receiving
Bibliography