Study “Perception and evaluation of Vehicle exterior noise by pedestrian in different traffic situations and different operating conditions” Date Nov. 2014

Vehicle exterior noise different traffic situations /operating conditions Based on the performance measurement of ICEV- noise, possible perception deficits of EV-/ HEV- noise should be shown 1. Pre Coming vehicle Vehicles: 14 ICEV (8 Petrol/6 Diesel) 4 EV 2 HEV 1 EV Synthetic Sound at 3 traffic-situations:

Vehicle exterior noise different traffic situations 2. Approaching vehicle parking lot 3. Slowing vehicle Cross-walk 49 dB(A) Very QuietQuiet 52 dB(A) 62 dB(A) Very Noisy Noisy 60 dB(A) / operating conditions

Starting Speed: 0 km/h ICEV EV HEV Synthetic Vehicle recognized Position Dummy- Head Microphon Backround Noise: Very Quiet / Quiet / Loud / Very Loud Recognition time 1. Pre Coming vehicle

Recognition time (s) Backround Noise: Very Quiet (49 dB(A)) EV / HEV Speed at micro 30 km/h ICEV Speed at micro 50 km/h EV Sound 1. Pre Coming vehicle

Backround Noise: Noisy (60 dB(A)) EV / HEV Speed at micro 30 km/h Recognition time (s) EV Sound ICEV Speed at micro 50 km/h 1. Pre Coming vehicle

Backround : Quiet and Noisy Recognition time (s) Biggest differences of Recognition-time between Quiet (52 dB(A) and Noisy (60 dB(A)) ! Only this 2 cases will shown No Corelation between Recognition time and Recognition SPL ! Examples … Recognition time (s) Recognition SPL 1. Pre Coming vehicle

Audi Q5 (HEV no AVAS) 30 km/h at micro Recognition time: 4,1 sec. Backround overall SPL: 57 dB(A) Vehicle overall SPL:52,4 dB(A) 1/3 Oct.: No level higher than Backround ! Mits. IMev (EV no AVAS) 30 km/h at micro Recognition time: 4,2 sec. Backround overall SPL: 57 dB(A) Vehicle overall SPL:61,5 dB(A) 1/3 Oct.: above 200 Hz each level higher than Backround Noise ! Recognition time: 1,4 sec. Backround overall SPL: 57 dB(A) Vehicle overall SPL:52,7 dB(A) 1/3 Oct.: Between 100 & 500 Hz levels higher than Backround Noise! Matiz (EV with AVAS) 30 km/h at micro 1. Pre Coming vehicle

2. Approaching vehicle 1. ICEV starting from idle (Diesel) „V-LL“ 2. ICEV after engine start (Diesel) „V-MS“ 3. EV without Sound „E-FZ“ 5 different sounds: 4. EV Synth. Starting- & Idling-Sound „Syn-LL“ 5. EV Synth. Starting- & NO Iddling-Sound „Syn“ „Idling“ Sound 4 „Syn LL“ Sound 5 „Syn“

Vehicle exterior noise … Recognition time (s) Overall Average Without distraction (backraound quiet) Without distraction (backraound noisy) With distraction (backraound quiet) With distraction (backraound noisy) Noise Idling Diesel Starting Diesel Recognition time (s) Overall Average Not Visually impaired Visually impaired Results:Time Only Small difference between ICE (0,82 s / 1,02 s) and Syn/Syn-LL (1,3 s) Results :Distance ICEV EV (no Sound) Conclusion: - Synthetic sound is needed - Stationary sound is not needed (with Syn-LL localisation not so easy) Syn = Syn-LL 1,3s Standard deviation ICE smaller than Syn / Syn-LL Nearly no difference between Syn-LL (1,24 s) and / Syn (1,31 s)

Vehicle exterior noise … 3. Slowing vehicle Cross-walk 1. ICEV stopped with idle (Diesel) „V-LL“ 2. ICEV stopped without idle (Start/Stop Diesel) „V-MS“ 3. EV stopped without Sound „E-FZ“ 5 different sounds: 4. EV Synth. stopped with idle-Sound „Syn-LL“ 5. EV Synth. stopped without idle-Sound „Syn“ Synthetic with idle-sound Synthetic with- out idle-sound EV without deccelaration-sound causes risks (big deviation) Nearly no difference between Diesel with/without Start/Stop Conclusion: Stationary sound gives no advantage in recognition of EV/HEV Results: Not heard anymore Waiting for change Nearly no difference between Syn-LL (+0,6 s) & Syn (+0,55 s)

Vehicle brakes? Vehicle accelerates? Vehicle exterior noise … Operation Status: acceleration – braking? Best recognition with fewest failures ? Sound sweeps (2 s) with Frequency alteration rate of 10%, 20%, 40%, 80%, 160% and 320% with and without backround noise of 55 dB(A) without backround noise braking with backround noise braking without backround noise acceleration with backround noise acceleration Frequency between 250 Hz and 400 Hz = 80% freqeuncy alteration

Vehicle exterior noise … Study Conclusions: Additional Sound is needed for detection of pre comming / approching EVs/HEVs Only a few individual bands of 1/3-octave have to be higher than backround noise bands Frequencies should be simular to deep-frequent ICE signals There is no correlation between recognition time and sound level Approaching (parking lot) & slowing (cross-walk) of EV/HEV without sound can‘t be recognised (early enough) Stationary Sound isn‘t necessary for Approaching (parking lot) & slowing (cross-walk) of EV/HEV Facceleration and braking should be shown by freqeuncy alteration between Hz

Thank you Vehicle exterior noise different traffic situations /operating conditions