automatic evaluation of automotive in-car communication systems · 2017-05-10 · automatic...

Automatic Evaluation of Automotive In-Car Communication Systems

Gerhard Schmidt

Christian-Albrechts-Universität zu KielTechnische FakultätElektrotechnik und InformationstechnikDigitale Signalverarbeitung und Systemtheorie

Digital Signal Processing and System Theory | Gerhard Schmidt | Automatic Evaluation of Automotive In-Car Communication Systems Slide 2

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Outline of the Presentation:

Agenda

Basics on in-car communication (ICC) systems

System setup for ICC evaluation

Work and research done so far

An attempt for automatic ICC evaluation

Evaluation groups

Estimating the system quality

Result visualization

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Basics on In-Car Communication Systems

Current Situation:

Application:

Passenger compartment

-5 … -15 dB*

*Acoustic loss (referred to the ear

of the driver)

Solutions:

Drivingdirection

Communication between passengers is difficult,because of the acoustic loss (especially front to rear).

Driver turns around – road safety is reduced.

Front passengers have to speak louder than normal – longer conversations will be tiring.

Improve the speech quality and intelligibility bymeans of an in-car communication system.

Automobiles, which are already equipped with the necessary audio and signal processing devices.

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Basics on In-Car Communication Systems

Solutions:

Improve the speech quality and intelligibility by means of an ICC system.

The ICC system records the speech by means ofmicrophones and improves the communication by playing back the signals via those loudspeakers thatare close to the listening passengers.

The figure on the right depicts only the processing units for the direction front-to-rear.

Loudspeakers

Loudspeakers

Rearpassengers

Driver

Frontpassenger

Micro-phones

Passenger compartment

Clipping detection,highpass filtering,

speaker localization,beamforming

Feedback andnoise

suppression Mixer

Feedbackcancellation

Automaticgain control,

noise dependentgain adjustment

Adaptive splitter,equalizer,

delay,limiter

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System Setup for ICC Evaluation

Example Setup:

Noise cancellation

Noise suppression

Speech separation

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ICC Evaluation – Work and Research Done So Far

Subjective Tests:

Several tests that try to answer ICC-related questions:

What is the optimal delay of an ICC system?

How does an ICC system influence the Lombard effect?

What are the effects of self perception due to ICC systems?

Objective Tests:

Signal-to-noise ratios (SNR, with and without ICC systems)

Reference-based distance measures

Speech transmission index (STI)

“Relative approach” (Gierlich, Kettler, Müsch, et al.)

Problems:

Not only the listener, but also the speaker isimportant in this application.

Participants should have a conversation as theirmain task while evaluating an ICC system.

The “reference” is not really clear yet.

Large variations in the subjects opinions and preferences was observed.

And many more …

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Work and Research Done So Far

Without an ICC system: With an ICC system:

Significant reduction of the Lombard effect (pitch frequency and loudness)

Details: R. Landgraf, et al.: Can You Hear Me Now? Reducing the Lombard Effect in a Driving Car Using an In-Car Communication System, Proc. Speech Prosody, pp. 479 - 483, 2016.

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Work and Research Done So Far

Details: R. Landgraf, et. al: Can you hear me now? Reducing the Lombard effect in a driving car using an In-Car Communication system, Proc. Speech Prosody, pp. 479 - 483, 2016.

Reduction of the Lombard effect due to ICC systems:

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An Attempt for Automatic ICC Evaluation

Evaluation Groups:

Quality is an complex concept, which requires a well defined evaluation strategy. Theevaluation strategy is split up into three evaluation groups:

Vehicle characteristics, ICC system behavior, Communication quality.

Each group consist of a variety of single measures, which have to be combined to a global quality evaluation.

Vehiclecharacteristics

Multi-dimensionalcharacterization, e.g.

vehicle size noise transducers

ICC systembehavior

measurements

Communicationquality

measurements

Evaluation result

ICC system quality

Communication quality

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Evaluation Groups – Vehicle Classification:

Mapping several vehicle measures on a normalized lowdimensional scale

Important dimensionsmight be:

Vehicle size

Transducerquality

Backgroundnoise

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Estimating the System Quality:

ICC system measurements

Delay

Noise increase and noise artefacts

“Speed” of the mixer

Several others

Communication measurements

STI

SNR

Several others


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Verlassen der Krankenhauses

Result Visualization:

Mainly (affine) linear mappings are used map the vehicle attributes to the “importance” weights of the qualitymeasurements and to “thresholds”within the individual measures.

Traffic light based color schemesallow for easy result interpretation.

Pie charts indicate on the importanceof the individual components.

… and a lot of further research is necessary here.

Vehicle measurements

Overall quality


ICC systemquality measurements

ICC systemquality


measurementsVehicle attributes

ICC systemattributes

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KiRAT overview of theICC system evaluation

Evaluation:

Automatic creation of realistic (calibrated)environmental conditions.

Creation and playback of test cases.

Automatic creation ofhierarchical html-basedresults.

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Thanks for the attention …

… maybe questions and/or comments!

automatic evaluation of automotive in-car communication systems · 2017-05-10 · automatic...

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