Post on 30-Aug-2020
Quiet Cars@BMW18 January 2011
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Quiet Cars@BMW.Challenges for Vehicle Safety and Acoustics.and Acoustics.
Alfred Zeitler, Robert Liebing, Armin Gräter & Jan Urbahn
Research & Innovation Center, MunichBMW of North America, LLC
Quiet Cars@BMW18 January 2011
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Introduction.Basic Attitudes and Strategic Statements.
�Corporate values of BMW are based on sustainabilityand social responsibility
�Need for specific safety measures for EVs and HEVs hasbeen acknowledged for a long time
�Research into evaluation methods has been performed in alliance with Daimler, Porsche and the Technical University alliance with Daimler, Porsche and the Technical University of Munich
�Acoustical warning devices are currently being developedfor all EVs and HEVs at BMW
�BMW has a supportive attitude towards research anddevelopment of non-acoustical approaches as well
�Note: not only pedestrians but also drivers will benefit fromwarning function (stress reduction)
Quiet Cars@BMW18 January 2011
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Introduction.BMW Approach and Responsibilities.
Psycho-
acoustics
VehicleSafety
Sound Design &
Engineering
Interdisciplinary team ofsafety specialists, acousticalengineers, sounddesigners& psychologists (Bavarian Assoc. of Blind & Visually Impaired People)
TechnicalUniversityof Munich
Quiet Cars@BMW18 January 2011
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Introduction.BMW Approach and Responsibilities.
Psycho-
acoustics
VehicleSafety
Sound Design &
Engineering
(Bavarian Assoc. of Blind & Visually Impaired People)
TechnicalUniversityof Munich
Interdisciplinary team ofsafety specialists, acousticalengineers, sounddesigners& psychologists
Quiet Cars@BMW18 January 2011
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Vehicle Safety.Risk Assessment.
Exploration of safety-relevant traffic scenarios
Top Critical Situations at v = 0-19 mph (0-30 km/h) Most Critical
Driving State
Risk
Level
stop & go, turning, green traffic light without
acoustic signal
driving at constant speed 6
public car parks (buildings) accelerating (and driving at
constant speed)
6
starting into the traffic after a stop on the lane accelerating 4
driving behind very slow and big vehicles (optically
and acoustically covered)
driving at constant speed 4
private car park / close to street accelerating 3
accident situation driving at constant speed 3
public car parks (open area) driving at constant speed 2
driving behind slow but small vehicles (visible, but
acoustically covered)
driving at constant speed 2
obstacle on lane (vehicle, bus, …) accelerating 2
Definition and priorization of situations
Quiet Cars@BMW18 January 2011
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BMW Approach and Responsibilities.Psychoacoustics.
Psycho-
acoustics
VehicleSafety
Sound Design &
Engineering
Interdisciplinary team ofsafety specialists, acousticalengineers, sounddesigners& psychologists (Bavarian Assoc. of Blind & Visually Impaired People)
TechnicalUniversityof Munich
Quiet Cars@BMW18 January 2011
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Psychoacoustics.Requirements for Exerior Noises of EVs.
Requirements Description
Perceptibility Vehicle noise can be detectedin background noise in a safe distance
Pleasantness Avoids annoyance at least and creates esthetic value at bestcreates esthetic value at best
Identifiability Noise is recognized as a vehicle
Dynamic Information Vehicle speed and acceleration/slowing is being conveyed
Localisation Position of vehicle can be perceived easily
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Psychoacoustics.Assessment of Perceptibility (Kerber, 2008). Calculation of Perception Distances.
Time varying sound-pressure of vehicle
Time varying sound-pressure of masker
Vehicle Speed
Perception-distance
Calculation of maskedthresholds according toFastl & Zwicker (2007)
Adapted from:Kerber (2008).
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62dB(A)
57dB(A)
Psychoacoustics.Algorithmic Prediction of Perceptibility.
CollisionPerceived in sufficient time Maskinglevel
dB(A)
52dB(A)
pedestrian
47dB(A)
5 m(16 ft)
10 m(33 ft)
15 m(49 ft)
20 m(66 ft)
25 m(82 ft)
Distance at perception
v=10km/h(6 mph)
Electric Vehicle
Hybrid E-Mode
Hybrid ICE-Mode
ICE Vehicle
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Psychoacoustics.Sound Level dB(A) vs. Perceptibility.
32
27 25 26
2123
1918
2220
10
20
30
40
Pe
rce
pti
bil
ity
[d
B]
Urban Traffic
20 20
16
2119
16 1714
19 19
Urban Babble
29
24 2427
23
15
28
18 18
22
Pink Noise
Maskers at 55 dB(A)
0
10
S-0
3
S-1
1
S-1
3
S-1
7
S-1
8
G-0
1
G-0
2
G-0
3
D-1
1
D-1
6
Sounds for EVs Gasoline Diesel
Pe
rce
pti
bil
ity
[d
B]
S-0
3
S-1
1
S-1
3
S-1
7
S-1
8
G-0
1
G-0
2
G-0
3
D-1
1
D-1
6
Sounds for EVs Gasoline Diesel
S-0
3
S-1
1
S-1
3
S-1
7
S-1
8
G-0
1
G-0
2
G-0
3
D-1
1
D-1
6
Sounds for EVs Gasoline Diesel
All Vehicle noises at 62 dB(A)
Perceptibility mainly depends on • masking properties of the background noise• level and character of the vehicle sound=> Sound level dB(A) is not sufficient for evaluation or prediction
Quiet Cars@BMW18 January 2011
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BMW Approach and Responsibilities.Sounddesign & Soundengineering.
Psycho-
acoustics
VehicleSafety
Sound Design &
Engineering
Interdisciplinary team ofsafety specialists, acousticalengineers, sounddesigners& psychologists (Bavarian Assoc. of Blind & Visually Impaired People)
TechnicalUniversityof Munich
Quiet Cars@BMW18 January 2011
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Challenges for Acoustics.Identifiablity of Electric Vehicles.
?
EVs should shave a distinguishable sound because many of their properties including dynamic performance are different.
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Challenges for Acoustics. Field Study with Blind Community.
�Participants: 5 members of the Bavarian Association of Blind and Visually Challenged people
� Location: vincinity of Munich
�Vehicles/sounds:�Vehicles/sounds:
� Original exterior noise of MINI E
� 8 synthetically-produced sounds
� ICE Vehicle (4-cyl. gas. engine)
�Vehicles passing by at a constant speed of 10 mp/h
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Challenges for Acoustics. Field Study with Blind Community.
Suitability
• ICE noise not suitable for EVs
MINI E Original Noise
MINI E SyntheticSounds
ICE Vehicle
Affectivity
very threatening very friendly
un-suitable very suitable • ICE noise is less surprising and therefore may initially appear less threatening due to familiarity
• However, a quick learning effect is expected
• Goal: EV to sound more pleasant than ICE
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Challenges for Acoustics.Requirements for Exerior Noises of EVs.
Requirements Description
Perceptibility Vehicle noise can be detectedin background noise in a safe distance
Pleasantness Avoids annoyance at least and creates esthetic value at best
Sound Character
creates esthetic value at best
Identifiability Noise is recognized as a vehicle
Dynamic Information
Vehicle speed andacceleration/slowing is beingconveyed
Localisation Position of vehicle can beperceived easily
Pitch shift component
Level shift
“Attention Catcher”
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Challenges for Acoustics. Perceptible and Pleasant Sound Character with Level Shift.
Loudness
Perceptible& pleasant sound
character
Level shift
+
Speed [mph]5 10 15 200
• Sounddesign with enhanced perceptibility
• Speed-dependent increase of level up to 16 mph (25 km/h)
• Pronunciation of load change through sound level
• Fade out from 16 mph (25 km/h)
“Attention Catcher”
Pitch shift component
+
+
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Challenges for Acoustics. Pitch Shift Reflecting Vehicle Dynamics.
Loudness
tonal components
Perceptible& pleasant sound
character
+
Level shift
Speed [mph]5 10 15 200
• Speed-dependent variation of tonal components
• Frequency range according to hearing sensitivity
• Slope of pitch shift to match subjective impression of acceleration
(under investigation)
“Attention Catcher”
Pitch shift component
+
+
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Challenges for Acoustics. “Attention Catcher” for Alerting against Departure.
Loudness“Attention catcher”
tonal components
Perceptible& pleasant sound
character
+
Level shift
Speed [mph]5 10 15 200
• Rapid boost of sound level on departure
• Immediate attenuation by analogy to a start-up sound of ICE vehicles
• No idle noise needed
“Attention Catcher”
Pitch shift component
+
+
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Challenges for Acoustics. Recommendation.
Loudness“Attention catcher”
tonal components
Perceptible& pleasant sound
character
Level shift
+
Speed [mph]5 10 15 200
Level shift
“Attention Catcher”
Pitch shift component
+
+“Enhancing safety with an environmentally friendly sound
with esthetic value.”
Quiet Cars@BMW18 January 2011
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Thank You for Your Attention.