Car Hands-Free Testing and Optimization: An Overview

  • Hans-Wilhelm GierlichEmail author


Testing of car hands-free systems needs to take into account the specific environment in the car. This chapter describes a variety of test methods and requirements applicable to car hands-free systems. The test scenarios describe the test setup in the car and the different considerations for microphone and loudspeaker placement. The performance parameters and test methods to achieve a good conversational speech quality are introduced and described. Parameters relevant in the single-talk situation, which mainly influence the speech quality in the listening situation, are discussed. Special consideration is given to the background noise presence where additional perception-based methods are described. Furthermore, tests and test conditions targeting the echo canceller performance in different conversational situations are presented. Besides the narrowband case, a special focus is given on wideband. The users’ expectations with regard to wideband are high, and the requirements for wideband car hands-free systems are high as well. The differences from the narrowband implementations are discussed. Finally, a method is given which allows a summary overview of a variety of results in one view, helping to better visualize a variety of test results and giving an easy-to-interpret overview of systems.


Car hands-free systems Performance parameter Noise cancellation Echo cancellation Testing and optimization procedures Speech quality 


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Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  1. 1.HEAD acoustics GmbHHerzogenrathGermany

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