ITU-T Recommendation P.emergency
The new ITU-T Work on
“Speech communication requirements for
emergency calls originating from
vehicles “
H. W. Gierlich
Managing Director Telecom
HEAD acoustics
Rapporteur Q.4 ITU-T SG12
A Typical Emergency Call
Public Safety
Answering Point
PSAP
MSD
Source: ADAC
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ITU-T Recommendation P.emergency
A Typical Emergency Call System Architecture in a Car
GPS (GLONASS)
receiver
3GPP TS 26.267
MSD
IVS
(minimum set of data)
(in vehicle system)
information source
data modem
Speech Codec
Radio Link
Hands-Free
for eCall
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Standards for Voice Quality in Car Hands-Free
VDA Specification for car hands-free systems
since 2001 – targeted to narrow-band integrated car hands-free
ITU-T P.1100: Narrowband hands-free communication
in motor vehicles
since 2008 – targeted to integrated, after-market car hands-free & headsets
Basis of ERA-GLONASS Standards
ITU-T P.1110: Wideband hands-free communication
in motor vehicles
since 2010 – targeted to integrated, after-market car hands-free & headsets
ITU-T P.emergency: Speech communication requirements
for emergency calls originating from vehicles
work ongoing since 09/2014 – targeted to car emergency call systems
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ITU-T Recommendation P.emergency
What is Different, what is Missing for Emergency Call Systems
Speech
Intelligibility
Sending
Speech
Intelligibility
Receiving
Speech Quality
Sending
Echo
Performance
Double Talk
Speech Quality
Receiving
Speech
Quality
Double Talk
Performance incl.
Performance
Intelligibility in DT
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Switching
Performance
Background Noise
Performance
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The Acoustical Situation in a Car
Sending –
speech pickup by
the microphone
Receiving –
speech reception by
the passengers
Coupling between
loudspeaker and
microphone
Background Noise –
pickup by
the microphone
Background Noise –
in addition to
speech in receive
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Main differences compared to car hands-free:
- Car is crashed
- System must work from all locations in the car
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ITU-T Recommendation P.emergency
System Constraints for eCall Systems
Costs – eCall systems should be produced at minimum costs
Reliability – eCall systems should be mostly independent of the car
systems, crash-proof
Component limitations
Potential “one box” design with small loudspeaker
No advanced microphone technology due to cost and space
requirements
Limitations in system placement
Need to be integrated into the car design during the design phase
General acoustical difficulties in a car cabin
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The Different Parameters Influencing the Quality of eCall Seech Services
Relevance to eCall speech services
Parameter in present standards
•
•
Delay
Frequency Response
Loudness Ratings
Distortions
System noise
Out of Band signals
Terminal Coupling Loss
Background noise
performance
Echo performance
Double talk performance
Switching performance
Comfort noise insertion
•
Probably less important
Should be targeted to intelligibility
Important basic parameter
Probably less important
Less important if below certain limits
Less important if below certain limits
Probably less stringent requirement sufficient
Important information in the background noise
should be preserved
Probably less stringent requirements needed
Important due to less disciplined conversation
Important due to less disciplined conversation
Less relevant
•
Speech Intelligibility
•
Most important, new tests required
•
•
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•
•
•
•
•
•
•
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ITU-T Recommendation P.emergency
The ITU-T SG 12 Approach
Major considerations for P.emergency in ITU-T
•
•
•
•
•
•
The recommendation will deal only and exclusively with emergency call
systems.
The main focus of this recommendation is on speech intelligibility as well
as on conversational aspects of speech quality such as double talk
capability.
Silent call scenarios are considered to be very important and need to be
integrated in P.emergency.
P.emergency will not consider post-crash scenarios, at least not in the
first versions
ITU-T SG12 recognizes the urgent need for such a Recommendation and
the goal is to finalize a first version already by May 2015.
Start with narrowband.
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The Main Parameters Considered in P.emergency
Parameter in and their purpose
•
•
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•
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Delay
Frequency Response
Loudness Ratings
System noise (idle channel)
Terminal Coupling Loss & additional
echo performance tests
Switching performance
_
Double talk performance
_
Background noise performance
_
Speech intelligibility in the presence
of background noise
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Ensure delay is below limits of relevant mobile stds.
Target to intelligibility rather than quality
Considers the different passenger locations in cars
Keep from existing standards
Important to ensure proper communication from the
car to PSAP, less demanding requirements than HFT
Important to ensure complete transmission of words
from the passengers to the PSAP side
Important parameter in conversation due to less
disciplined behavior of injured passengers
Taking into account the transmission of noise in
silent calls (no passenger speaking)
Focusing on intelligibility rather than on quality,
ensuring a high intelligibility with background noise
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ITU-T Recommendation P.emergency
Challenges in Testing and Requirements for eCall Speech Services
•
•
•
•
Speech Intelligibility
• In sending no objective methodology available
• In receiving the application of existing methods is studied (not likely to be
included I the first version)
“Work-arounds”
• Adaptation of frequency response characteristics
• Additional loudness requirements for different positions in the car
New focus in background noise situations:
• High intelligibility with background noise
• Preserve “naturalness” & “recognizability” of the background noise
Preserve double talk capability as much as possible with special focus on
intelligibility during double talk
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Considerations for Speech Intelligibility Testing in eCall Systems
•
Speech Intelligibility in receiving
• More “classical” situation – similar to speech intelligibility in rooms
• Potential application of existing methods such as
•
•
•
•
SII (speech intelligibility index),
STIPA (speech transmission index for public address systems)
RASTI (rapid speech transmission index)
Speech Intelligibility in sending
• No well performing objective test method available
• Performance evaluation potentially possible using “second order”
parameters such as
•
•
•
Optimized frequency response characteristics,
Evaluation of switching and double talk performance with focus on speech
intelligibility
Consideration of eCall relevant noise types
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ITU-T Recommendation P.emergency
Background Noises in eCall Senarios
Simulation of a crashed vehicle by testing with the background noise rcorded
with open windows
analysis
analysis
p/dB[Pa]
0
dBSPL(A)
Spectrum avg. FFT Size:4096 Overlap:0,0% Hanning
100
90
80
70
60
50
40
30
20
10
0
-20
Noise Level
left ear
69,3 68,2
right ear
73,8
-40
68,0
59,4
53,5
41,7 40,0
-60
36,4 33,9
-80
Car 130 kmh
20
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-100
Full Size Car 130 kmh binaural
VW Touran, H ighway parking, windows closed
VW Touran, H ighway parking, windows open
Highway,
Highway,
Quiet street,
Quiet street,
windows open windows closed windows open windows closed
50
100
200
f /H z 1000 2000
5000
-120
10k
20k
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Timeline P.emergency
FNC 2014 conclusion: develop a standard
specifically targeted to emergency call systems
Proposal of an new Recommendation
P.emergency
Decision on start of work in ITU-T SG12 – Q.4
First Draft (based on ITU-T standards P.1100 and
P.1110)
Invitation of experts/stakeholders for a Rapporteur
Meeting hosted by HEAD acoustics
Define most relevant parameters and test
procedures
Validate new requirements
Final draft (first version)
Proposed date for consent
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P.emergency
March 2014
April 2014
Sept. 2014
Dec. 2014
Ongoing
May 2015
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ITU-T Recommendation P.emergency
Dr.-Ing. H. W. Gierlich
info@head-acoustics.de
www.head-acoustics.de
© Copyright HEAD acoustics GmbH
© HEAD acoustics GmbH
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