Researches and Applications for Automotive Field

Andrea Azzali, Eraldo Carpanoni, Angelo Farina

Universityof Parma

Topics

University of Parma

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

University of Parma

Innovative dynamic analysis technique

AQT Tool

University of Parma

Goal:⇨Substitute classical analysis based on FFT with

dynamic analysisReasons:

⇨FFT characterize system only in steady state condition

BUT

⇨Hearing system is more sensible vs transient

⇨Musical signal is not a steady state signalSolution:

⇨Aqt analysis system

Innovative dynamic analysis technique

University of Parma

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

AQT Analysis system

University of Parma

Objective evaluation system

Evaluation Test

Objective evaluation system

University of Parma

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)

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

University of Parma

Objective evaluation system

University of Parma

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)• ……..

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

University of Parma

Virtual listening system

University of Parma

Listening room

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.

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

University of Parma

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

PC&

Audio Card(Digital Out)

DSP SHARC 21161

DSP SHARC 21161

PC&

Audio Card(8 In, 10 Out)

Power amplifier

Power amplifier

Power amplifier

Power amplifier

Frontstereo dipole

Rearstereo dipole

2 lateralloudspeakers

2 bottomloudspeakers

Subwoofer

Virtual listening system

Virtual system Plant:

Stereo Dipole Front

Stereo Dipole Rear

Surround loudspeake

rCentral Channel

Algorithm for sound field correction

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+1Platform:

⇨DSP boardTechnique:

⇨FIR Filtering

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

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

University of Parma

Digital system simulation

University of Parma

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 PCGoal:

⇨ 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!!!

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

Car inside digital system simulation

Simulation Block Diagram:

NotebookPCIMCA

MultichannelAudio card

MultichannelPower Amplifier

Standardsystem

Stereo dipolesystem

5+1 surroundsystem

Reliable measure technique

University of Parma

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 degrees0o-15o +15o