High Quality Background Noise Simulation: the ETSI STF 273 Project

Transcription

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

2 Introduction Scope: Background noise transmission contributes perceived overall speech quality Background noise simulation scenario for laboraty use Objective performance evaluation of terminals and codecs Subjective evaluations in third party listening tests or conversational tests 2

3 Requirements Requirements for recording Easy use Easy to calibration Capable for wideband recordings reasonably priced Requirements for simulation arrangement Easy to setup Easy to calibrate Insensitive concerning test rooms and positioning of test-objects Various types of test-objects Reasonably priced 3

4 Reproductions methods Different methods available: 5.1 surround sound technique IOSONO Eidophonie 4.1 loudspeaker arrangement NTT background noise database Selected method: 4.1 loudspeaker arrangement Applicable in office rooms and cars 2m Subwoofer 2m 2m 4

5 Recordings for 4.1 in office rooms Recordings for the setup in office rooms with Artificial heads (ITU-T 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 5

6 Calibration & equalization Calibration & equalization setup for use in standard office rooms: Procedure: 1. Equalization for each of the four loudspeakers 2. Level adjustment for each loudspeaker 3. Equalization for the two lefthand and two right-hand loudspeakers 4. Equalization and level adjustment for the subwoofer 5. Delay compensation 6. Overall equalization Playback Reference Channel 2m Subwoo fer 2m Analyser (2-channel) 2m 2m 6

7 Accuracy of the 4.1 reproduction system Sound sources and simulation: Comparison of original and simulated sound field at the HATS left and right ear L/dB[Pa] Frontal left loudspeaker Sound Source Source 2: 2: Loudspeaker Original Simulation L/dB[Pa] Frontal right Sound loudspeaker Source 1: Loudspeaker Sound Subwoofer Source 3: Sound Source 3: Computer AH_right_original.3rdOctave(4096,50.0%) AH_right_simulated.3rdOctave(4096,50.0%) f/hz k 20k AH_left_original.3rdOctave(4096,50.0%) AH_left_simulated.3rdOctave(4096,50.0%) f/hz k 20k 7

8 Accuracy of the 4.1 reproduction system Simulation with displaced HATS 10 cm to frontal right, 10 cm backwards left L/dB[Pa] L/dB[Pa] AH_left_original.3rdOctave(4096,50.0%) AH_left_fr_10cm_simulated.3rdOctave(4096,50.0%) AH_left_bl_10cm_simulated.3rdOctave(4096,50.0%) f/hz k 20k AH_right_original.3rdOctave(4096,50.0%) AH_right_fr_10cm_simulated.3rdOctave(4096,50.0%) AH_right_bl_10cm_simulated.3rdOctave(4096,50.0%) f/hz k 20k 30 cm to frontal right L/dB[Pa] L/dB[Pa] AH_left_original.3rdOctave(4096,50.0%) AH_left_fr_30cm_simulated.3rdOctave(4096,50.0%) f/hz k 20k AH_right_original.3rdOctave(4096,50.0%) AH_right_fr_30cm_simulated.3rdOctave(4096,50.0%) f/hz k 20k 8

9 Comparison of terminal performance Headset Mobile phones Headset_original.3rdOctave(4096,50.0%) Headset_simulated.3rdOctave(4096,50.0%) f/hz k 20k MobPh2_original.3rdOctave(4096,50.0%) MobPh2_simulated.3rdOctave(4096,50.0%) f/hz MobPh1_BGN SP_original.3rdOctave(4096,50.0%) MobPh1_BGN SP_simulated.3rdOctave(4096,50.0%) f/hz Desktop HFT Wideband conference system DesktopHFT_original.3rdOctave(4096,50.0%) DesktopHFT_simulated.3rdOctave(4096,50.0%) f/hz WB_HFT_original.3rdOctave(4096,50.0%) WB_HFT_simulated.3rdOctave(4096,50.0%) f/hz k 9

10 4.1 simulation system in cars Modified setup: Background noise Loudspeaker equalizer HFT Choose equalization microphone: Terminal microphone (if accessible) Pair of cardioid microphones Subwoofer 10

11 Recordings for 4.1 in cars 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 11

12 Calibration & equalization in cars Calibration & equalization setup with terminal microphone Procedure: 1. Equalization for each of the four loudspeakers 2. Level adjustment for each loudspeaker 3. Equalization for the two left-hand and two righthand loudspeakers 4. Equalization and level adjustment for the subwoofer 5. Delay adjustment 6. Overall equalization Playback Reference Channel Analyser Subwoofer 12

13 Calibration & equalization in cars Calibration & equalization setup with a pair of cardioid microphones Procedure: 1. Pairwise equalization for the left-hand loudspeakers 2. Level adjustment for the left-hand loudspeakers 3. Pairwise equalization and level adjustment for the right-hand loudspeakers 4. Equalization and level adjustment for the subwoofer 5. Delay compensation 6. Overall equalization Playback Reference Channel Analyser (2-channel) Subwoofer 13

14 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 CardioidMic_right_originalCar.3rdOctave(4096,50.0%) CardioidMic_right_simulatedCar.3rdOctave(4096,50.0%) f/hz k 14

15 Comparison of terminal performance Microphone Array -10 Hands-free telephone 2 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 Hands-free telephone 1 HFT1_originalCar.3rdOctave(4096,50.0%) 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(4096, f/hz

16 Content of the draft DEG Introduction Overview of existing methods Recording arrangement Setup & equalization description for the playback arrangement in office rooms and cars Verification of the accuracy in office rooms and cars Background noise database 16

17 Conclusion & Further steps 4.1 simulation system suitable for simulations in standard office rooms Cars Easy setup, calibration and equalization Next steps: completion of the background noise database recording of the reference wideband speech material for conducting the basic subjective tests in STF 294 Developing an objective method for speech quality evaluation in the presence of background noise (STF 294) 17