Researches and Applications for Automotive Field

1. University of Parma Researches and Applications for Automotive Field Andrea Azzali, Eraldo Carpanoni, Angelo Farina

2. University of Parma Topics • Main Researches: • Objective evaluation index for audio performance characterization and Innovative Analysis technique for musical signal (AQT system) • Virtual car cockpit for system comparison • Algorithm for audio equalization (AQT, CTC) • Simulation of digital system staying inside car cockpit • Robust measuring technique for reliable and stable characterization with IR

3. University of Parma • Innovative dynamic analysis technique AQT Tool

4. University of Parma Innovative dynamic analysis technique • Goal: • Substitute classical analysis based on FFT with dynamic analysis Reasons: • FFT characterize system only in steady state condition BUT • Hearing system is more sensible vs transient • Musical signal is not a steady state signal Solution: • Aqt analysis system

5. University of Parma AQT Analysis system • Features: • Use transient stimulus instead steady-state ones • Find psychoacoustics response more closed to real perceived curve than FFT response • Find resonance in cockpit and tail that affect hearing • Useful during car system development Output: • Articulation parameter • Energy deviation from best curve corresponding to pleasant hearing inside the car

6. University of Parma Objective evaluation system Evaluation Test

7. University of Parma Objective evaluation system • Activity in Collaboration with CRF: Fiat Research Centre • Goal: • Reduce time needed for system characterization during car system development • Obtain Reliable characterization of hearing inside the car and develop a series of objective parameter useful as project statement Status: • In progress (deadline 24/12/2003)

8. University of Parma Objective evaluation system • Proceeding: • Study of main features that affect subjective evaluation of car system >> OUTPUT: Subjective Index of performance (New IPA) • Study of a series of objective parameter able to describe this features >> OUTPUT: statement • Study of correlation between subjective and objective parameter >> OUTPUT: Objective Index of Performance

9. University of Parma Objective evaluation system Subjective evaluation parameters: • Intensity of Sound and SPL MAX. • Distortion. • Spectral attributes. • Spatial attributes . • Speech clarity and intelligibility. • Low frequency quality. • Articulation and clarity of sound (Fidelity) • Objective Parameters • Dynamic response of car inside (AQT Method) • Articulation and energy recovery at low frequency (AQT) • Spatial parameter (IACC and localization index) • Speech clarity (STI) • ……..

10. University of Parma Objective evaluation system • Current activities: • Preparation of subjective test based on questionnaire developed for subjective database and statistical process • Study of listening room as standard listening test environment instead of car inside

11. University of Parma Virtual listening system Listening room

12. University of Parma Virtual listening system • Goal: • Fast comparison between different car audio system • Detailed highline of difference Reasons: • The tests not be done in the car because of the high switching time and the unavailability of the car after long time. • Features: • Fast switch between different configurations • Capability of comparison by audio system of the cars nevermore available • The listening room reproduce the binaural recorded tracks in the car and doesn’t insert any apparent alteration.

13. University of Parma Virtual listening system • Proceeding: • Record with dummy head Audio CD for subjective test and signal for characterization of car inside • Reproduce the Audio track, recorded in several car, in Virtual system • Use for audio comparison an automatic software developed in VB

14. Power amplifier Front stereo dipole DSP SHARC 21161 Power amplifier Rear stereo dipole PC & Audio Card (Digital Out) PC & Audio Card (8 In, 10 Out) Power amplifier 2 lateral loudspeakers DSP SHARC 21161 Power amplifier 2 bottom loudspeakers Subwoofer Virtual listening system • Virtual system: • Double stereo dipole • Two central channel for voice and monophonic signal • Two surround channel for reproduction of high uncorrelated signal and aimed to recreate lateral contribution from loudspeaker in car

15. Stereo Dipole Front Surround loudspeaker Central Channel Stereo Dipole Rear Virtual listening system Virtual system Plant:

16. University of Parma Algorithm for sound field correction

17. University of Parma Algorithm for sound field correction • Existing algorithms: • Time delay alignment • Stereo dipole for new configuration system (dedicate loudspeaker + central channel) • Psychoacoustic curve correction (Aqt Filter) Algorithms under test • Stereo dipole for standard system configuration • Resonance and tail correction system (Aqt Filter) • In the future >> Surround system: 5+1 Platform: • DSP board Technique: • FIR Filtering

18. University of Parma Algorithm for sound field correction • Time delay alignment: • Compensate the time difference existing between the time arrival of the direct sound of the two hearing channel • Create a virtual symmetric system • Enhance spatial sensation and create a wide scene in the driver position • Stereo dipole for new configuration system: • Need a couple of loudspeaker for each seat • Enhance spatial sensation and create a wide scene in all the listening position • Perform Cross-Talk and reduce resonance and reflection effects on the hearing

19. University of Parma Algorithm for sound field correction • Psychoacoustic curve correction: • Invert dynamic curve response of car cockpit really perceived by hearing system • Perform more pleasant filter than standard inversion technique • A tool is already developed to perform this: AQT Tool

20. University of Parma Digital system simulation

21. Digital system simulation • Overview: • it’s a difficult task compare a lot of algorithm and set of coefficients at the same time on DSP board Solution >> Simulation System on PC • Goal: • Simulate different digital system for correction of the response inside the car: Stereo Dipole Filtering, IIR, FIR,AQT Filter, 5+1 surround system • Compare different configuration staying in listening position Features: • Let us to compare all the algorithms in real time and perform a fast switching between different configuration (Ex: 5+1 vs Cross Talk) • Let us to compare in a fast way several set of coefficients of FIR, IIR, AQT filter and to choose the set that retrieves the best performance and pleasure • PERMIT ON THE ROAD TEST!!!

22. Car inside digital system simulation • Simulation system: • A Notebook • Existing Software: • digital block performing several algorithm • Accept extern block programmed in VST standard • We already have all the block that permit the simulation of the entire set of developed algorithm • We have the know-how to perform new VST plug-in for new algorithm • A multichannel (10 or more) Sound Card with PCIMCA interface as Echo Layla >> WE NEED IT!!! • Amplifiers to drive all the loudspeaker

23. Car inside digital system simulation • Simulation Block Diagram: Standard system PCIMCA Multichannel Audio card Multichannel Power Amplifier Notebook Stereo dipole system 5+1 surround system

24. University of Parma Reliable measure technique

25. -15o +15o 0o Reliable measure technique for IR • Goal: • Introduce the Impulse Response as standard measure for characterization of the car inside • Introduce the use of Cool-Edit and Aurora for IR measure • Introduce AQT Tool as advanced analysis system • Perform reliable and repeatable measures of response inside the car testing several procedures of average of binaural recording THE ACTUAL APPROACH: Binaural recording of IR with rotating dummy head by step of 15 degrees