The VDA Specification for car hands- free: A step towards ... · 2 dates ITU-T Outline o Speech...
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International Telecommunication Union ITU-T Workshop on Standardization in Telecommunication for motor vehicles ITU Headquarters, 24-25 November 2003 The The VDA VDA Specification for car hands Specification for car hands - - free free : A : A step towards improved speech step towards improved speech quality quality in in car type environments car type environments . . Balduin, W. (Ford AG); Best, H.(Adam Opel AG); Dietz, M. (BMW); Eisner, G. (Volkswagen AG); Gierlich, H.W. (HEAD acoustics GmbH); Hanke, A. (Audi AG); Heise, B. (Porsche AG); Schaible, M. (DaimlerChrysler AG)
Transcript of The VDA Specification for car hands- free: A step towards ... · 2 dates ITU-T Outline o Speech...
International Telecommunication Union
ITU-T Workshop on Standardization in Telecommunication for motor vehiclesITU Headquarters, 24-25 November 2003
TheThe VDA VDA Specification for car handsSpecification for car hands--freefree: A : A step towards improved speech step towards improved speech
qualityquality in in car type environmentscar type environments..
Balduin, W. (Ford AG); Best, H.(Adam Opel AG); Dietz, M. (BMW); Eisner, G. (Volkswagen AG); Gierlich, H.W. (HEAD
acoustics GmbH); Hanke, A. (Audi AG); Heise, B. (Porsche AG); Schaible, M. (DaimlerChrysler AG)
2dates
ITU-T
Outline
o Speech Quality: The Relevant Parameterso Signal Processing in Car Hands-Free Systemso The VDA Approach:
� Test Setup� Tests� Test Signals
o Requirements for further Work andStandardization
3dates
ITU-T
Speech Quality from the Users Perspective
speechquality
talkingsituation
listeningsituation
conversationalsituation
4dates
ITU-T
Choice and Design of SubjectiveTests Methods
correlationto instrumentallaboratory tests
factorsthat cause difficultiesin listening (type A)
value selection
parameter identificationand definition
quality assessment
Comparison of implementations data base
for further tests
quality predictionunder realistic
network conditions
testdesign
factorsthat cause difficulties
in talking (type B) factorsthat cause difficultiesin conversation (type C)
5dates
ITU-T
Parameters Relevant to Quality
o Auditory perceived parameters which determine the speech quality of hands-free terminals:
� Quality of background noise transmission � (Speech) sound quality� Delay and echo� Double talk capability� Switching and echo during double talk� Loudness� (System) noise
6dates
ITU-T
Hands-Free Signal Processing
Modulation/
DemodulationH(f )
- NLP
CNEC
Decoder
Coder
Loudspeaker
DecoderComfort Noise
Microphon �(Array)
EC Attenuation Coder
Noise-reduction
+
NR
e.g. GSM - Modul
Speech Recognition
7dates
ITU-T
VDA: The Test Setup
� real car cabin � installed hands-free
terminal� System simulator
(GSM, ...)� Background noise
simulation� HATS Head and
Torso Simulator (ITU-T P.58, P.581)
� VDA Specification or HQS-HFT
Subwoofer
HFT
Measure-ment system
SystemSimulator
(HF)
Backgroundnoise
Loud-speakerequalizer
8dates
ITU-T
The Structure of the VDA Specification
o Microphone measurements:� Sensitivity, frequency responses, ambient
noise reduction�o Hands-free measurements:
� Delay� Standard parameters (LR, responses, noise,
out of band �)� Echo related parameters (TCL, vs. time,
spectral�)� Switching characteristics� Double talk parameters (attenuation, echo)� Background noise transmission parameters
9dates
ITU-T
Microphone Measurements
� Sensitivity� linearity� distortions� frequency response� idle noise� ambient noise reduction
Two test principles:
� sensitivity� linearity� distortions
Measurements in anechoic
test conditionsMeasurements in the car cabin
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ITU-T
Hands-free tests
! Frequency Response! Loudness Ratings! Distortions! Noise! Out of Band signals! Terminal Coupling Loss
Standard-parametersin the car
Advanced tests in the car
! Delay! Background Noise suppression
(DeLSM! Distortions! Echo loss - time variant,
spectral! Double talk performance! Background noise performance! Comfort noise insertion
11dates
ITU-T
Testsignals:
Speech-like, but adapted to the specific measuerement task:
�Composite Source� Signals
Artificial Voice
ModulatedVoicedSound
12dates
ITU-T
Testsignals (CSS)
Pseudo Noise
Voiced Sound
Pause
Signal description in ITU-T P.501
Composite source Signals
13dates
ITU-T
(Noise)- Measurement with Activation Test Signal
Test signalactivation CSS-28.7 dBPa
Test / Analysisafter activationwindow length 1s (smaller if necessary!)
RequirementsGSM < -64 dBm0(P)(3GPP)
Analysis
14dates
ITU-T
Terminal Coupling Loss
Test signalActivation artificialvoice, -16 dBm0pseudo noise sequence -3 dBm0
Test / AnalysisTerminal coupling loss according to G.122
Requirements> 40 dB (3GPP)> 46 dB recommended (ITU)> 33 dB at maximum volume
Analysis
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ITU-T
Double Talk Performance
single talkanalysis
Test signalCombination of CS signals
Test / AnalysisLevel vs. time
RequirementsType ofclassification!
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ITU-T
Classification based on ITU-T Rec. P.340
Type 1 Type 2 Type 3
SubjectivelyRelevantParameter
Full duplexcapability
Partialduplex
capability(in P.340 and
VDA moreprecise)
No duplexcapability
ObjectiveParameter• aH,SND,DT• aH, RCV,DT• Echo
attenuation
< 3 dB< 3 dB≥ 37 dB
12 - 3 dB10 - 3 dB
36 - 21 dB
> 12 dB> 10 dB< 21 dB
17dates
ITU-T
Summary
o Speech quality has to consider the conversational situation - the listening situation, the talking situation and double talk
o Objective parameters are combined by standard parameters as well as specific parameters determining double talk and background noise transmission quality
o Specific test signals are suited for the detailed evaluation of the various parameters
18dates
ITU-T
To Do: Requirements for Future Work
o Speech quality in the presence of background noise
o Quality of the noise transmissiono Dynamic background noise simulationo Speech quality in combination with
varying network qualityo Requirements for wideband
conversational speech quality
