Background Noise Simulation and Hands- Free Testing in a Car: The ETSI STF 273 Project and Its Impact on Car Hands-Free Testing

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1 International Telecommunication Union Background Noise Simulation and Hands- Free Testing in a Car: The ETSI STF 273 Project and Its Impact on Car Hands-Free Testing H.W. Gierlich, S. Völl GmbH

2 The Car Hands-Free Problem Background noise Microphon (Array) Car hands-free system: including audio signal processing, coding and RF-interface Loudspeaker Speech Recognition 2

3 Hands-Free Signal Processing Microphon (Array) Noisereduction Echo - Cancellation Attenuation Coder - NLP NR Coder H(f ) Modulation / Demodulation + Decoder Loudspeaker CN e.g. GSM - Modul Speech Recognition Comfort Noise Decoder 3

4 Parameters Relevant to Quality (and covered mostly by the tests in the VDA specification) o Speech quality as perceived by the user: (Speech) sound quality Delay and echo Double talk capability Switching and echo during double talk Loudness (System) noise Quality of background noise transmission 4

5 real car cabin installed hands-free terminal System simulator (GSM,...) HATS Head and Torso Simulator ( P.58, P.581) Tests: VDA Specification / new work in SG12 Background noise simulation ETSI STF 273 Test Setup Background noise System Simulator Measurement system Loudspeaker equalizer (HF) HFT Subwoofer 5

6 The ETSI STF 273 Project o Scope: Defining background noise simulation scenario for laboraty use to be used for Objective performance evaluation of terminals and codecs Subjective evaluations in third party listening tests or conversational tests => ETSI Guide EG

7 Requirements o Requirements for the recording procedure Easy to use Easy to calibrate Capable for wideband systems o Requirements for the simulation arrangement Easy to setup Easy to calibrate Insensitive to different types of test rooms and positioning of test-objects Applicable to all types of terminals 7

58) or Binaural probe microphone (MIRE technique) Artificial Head (AH)

8 The Recording Setup o Recordings for the setup in office rooms with Artificial heads ( Rec. P.58) or Binaural probe microphone (MIRE technique) Artificial Head (AH) artificial AH or head BM Equalizer equalizer right or Binaural Microphone worn by a subject (BM) AH or BM Equalizer left Upload to Data Base 8

9 The Background Noise Simulation Setup: Technique Playback from database 2m Subwoofer 2m 2m 2m Terminal under test Analyser (1/2-channel) 9

Comparison of Terminal Performance Headset L/dB[V] Mobile phone L/dB[V] MobPh1_BGN

0%) MobPh1_BGN SP_simulated.3rdOctave(4096,50.

0%) Headset_simulated.3rdOctave(4096,50.

conference system L/dB[V] DesktopHFT_original.3rdOctave(4096,50.

10 Comparison of Terminal Performance Headset L/dB[V] Mobile phone L/dB[V] MobPh1_BGN SP_original.3rdOctave(4096,50.0%) MobPh1_BGN SP_simulated.3rdOctave(4096,50.0%) f/hz Headset_original.3rdOctave(4096,50.0%) Headset_simulated.3rdOctave(4096,50.0%) f/hz k 20k -90 Desktop HFT L/dB[V] Wideband conference system L/dB[V] DesktopHFT_original.3rdOctave(4096,50.0%) DesktopHFT_simulated.3rdOctave(4096,50.0%) f/hz Green original Red - simulated WB_HFT_original.3rdOctave(4096,50.0%) WB_HFT_simulated.3rdOctave(4096,50.0%) f/hz k

11 4.1 Simulation System in Cars o Modified setup: Background noise Loudspeaker equalizer HFT o Choose equalization microphone: Terminal microphone (if accessible) Pair of cardioid microphones Subwoofer 11

12 Recording Setup in Cars o Driving with constant speech when equalizing with terminal microphone Terminal s microphone Upload to Data Base when equalizing with a pair of cardioid microphones artificial Cardioid head microphone equalizer right left Cardioid microphone right Upload to Data Base 12

13 4.1 Playback Setup in Cars Playback from database Reference Channel Subwoofer Analyser 13

14 o Accuracy of the 4.1 System in Cars After equalization with a pair of cardioid microphones: left microphone L/dB[Pa] right microphone L/dB[Pa] CardioidMic_left_originalCar.3rdOctave(4096,50.0%) CardioidMic_left_simulatedCar.3rdOctave(4096,50.0%) f/hz k Green original Red - simulated CardioidMic_right_originalCar.3rdOctave(4096,50.0%) CardioidMic_right_simulatedCar.3rdOctave(4096,50.0%) f/hz k 14

Comparison of Terminal Performance Microphone Array L/dB[V] Hands-free telephone 2 L/dB[V] -10-20 MicArray_originalCar.3rdOctave(4096,50.0%) MicArray_simulatedCar.3rdOctave(4096,50.0%) 100 200 500 f/hz 1000 2000 5000 HFT2_originalCar.

15 Comparison of Terminal Performance Microphone Array L/dB[V] Hands-free telephone 2 L/dB[V] MicArray_originalCar.3rdOctave(4096,50.0%) MicArray_simulatedCar.3rdOctave(4096,50.0%) f/hz HFT2_originalCar.3rdOctave(4096,50.0%) HFT2_simulatedCar.3rdOctave(4096,50.0%) f/hz L/dB[V] Hands-free telephone 1 L/dB[V] HFT1_originalCar.3rdOctave(4096,50.0%) -90 HFT1_simulatedCar.3rdOctave(4096,50.0%) HFT1_simulatedCar_-3dBfront_+5dBrear.dat.3rdOctave(4096,50.0%) f/hz HFT1_originalCar.3rdOctave(4096,50.0%) HFT1_simulatedCar_-3dBfront_+5dBrear_sim.structureborne.3rdOctave( f/hz Green original Red - simulated 15

16 Conclusions & Further Steps o 4.1 simulation system suitable for simulations in standard office rooms Cars o Easy setup, calibration and equalization o Next steps: setup of background noise database Sound sources for play back in office rooms and cars Development of an objective method for speech quality evaluation in background noise situations 16

High Quality Background Noise Simulation: the ETSI STF 273 Project

High Quality Background Noise Simulation: the ETSI STF 273 Project DEG 202 396-1: Background noise simulation technique and background noise database H.W. Gierlich, S. Völl, HEAD acoustics GmbH 1 Introduction