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Session A Saturday, May 12 9:30 - 13:00 hr Room B

Automotive Audio

Chair: Richard Stroud, Delphi Delco Electronics, Kokomo, IN, USA

9:30 hr A-1
IPA - A Subjective Assessment Method of Sound Quality of Car Sound Systems
Emanuele Ugolotti (1), Angelo Farina (2) & Gino Gobbi
(1) ASK Industries, Reggio Emilia, Italy
(2) University of Parma, Parma, Italy

The paper describes a new subjective evaluation method of the acoustical quality produced by a sound system inside a car compartment. The method produces a single rating number, called IPA (Index of Performance Acoustic), defined as a weighted average of the subjective responses to a questionnaire, being compiled during listening tests conducted with the subject seating inside different cars. The paper describes the details of the subjective test, and focuses on the choice of questions in the questionnaire and of the weight to be employed. The principal innovation of the new method is the fact that the weights are changed according to the reliability of the subject (which is also inferred from the questionnaires), and thus the evaluation is very robust and almost immune from the inclusion in the panel of completely unreliable evaluators.
Paper 5281

10:00 hr A-2
New Planar Magnetic Loudspeakers for Automotive Sound Systems
David Clark (1) & Annabelle Edge (2)
 DLC Design, Wixom, MI, USA
 Sonigistix Corporation, Richmond, Canada

A series of planar magnetic drive units has been developed to target specific problems in automotive sound systems that are not fully addressed by conventional speakers. The naturally flat form factor of planar magnetic drive units allows them to placed in more nearly optimal locations for imaging performance. Also contributing to superior imaging is the directivity of the large planar radiating surface. Aperture restriction and use of acoustic lens are methods of controlling this directivity.
Paper 5282

10:30 hr A-3
AQT - A New Objective Measurement of The Acoustical Quality of Sound Reproduction in Small Compartments
Angelo Farina (1), Gianfranco Cibelli (2) and Alberto Bellini (1)
(1) University of Parma, Parma, Italy
(2) ASK Automotive Industries, Reggio Emilia, Italy

The paper describes a new measurement technique of the acoustical quality produced by a sound system. The method is called AQT (Acoustic Quality Test), and produces a graphical representation of the dynamic response of the system to tone bursts at various frequencies. This makes it possible to visualize simultaneously the steady frequency response, the transient response and the signal-to-noise ratio. The new method revealed particularly useful for describing the performance of a sound system coupled with a small, noisy reproduction space, as it is the case for car audio systems.
Paper 5283

11:00 hr A-4
Subjective Evaluation of 2-Channel vs Surround Formats in Vehicles
Neal House
Harman/Becker Automotive Systems, Martinsville, IN, USA

A study was done to subjectively compare and rank the sound field characteristics of a vehicle equipped with a high end home surround sound processor and to assess compatibility of several discrete and matrix decoding modes in combination with both discrete and down mixed source materials. A vehicle was fitted with a 3/4-loudspeaker arrangement (7.1) and evaluated with optimized amplitude balance, using all loudspeakers, for all encoding and decoding modes. Comparisons were also done in a 3/ 4 listening room for reference. The study design details and analysis results are reported.
Paper 5284

11:30 hr A-5
Performance of Loudspeaker Whizzers
John Stewart
Harman/Becker Automotive Systems, Martinsville, IN, USA

The auxiliary loudspeaker cone known as a whizzer is used to gain high frequency amplitude response in applications where cost or weight constraints prohibit a separate, dedicated high frequency transducer. Usually attached to the front edge of a dynamic loudspeaker voice-coil former at the apex of the main cone, its target performance range is from 5 kilohertz (kHz) to 20 kHz. The functional mechanism of the whizzer is not particularly well understood. Performance prediction is difficult. Related here are test results, laser vibrometer images, anecdotes, and design directions that may aid future whizzer designs and stimulate the development of better design tools.
Paper 5285

12:00 hr A-6
Multimedia in Cars: The Use of Logic 7 Surround Processing as the Solution to the Challenge of Providing Surround Sound in Cars from all 2 Channel and Encoded 5.1 Sources
Timothy Nind
Harman/Becker Automotive Systems, Bridgend, UK

The arrival of multimedia in car entertainment presents a challenge for the audio playback system. The majority case will continue to be the playback of 2 channel sources such as CD and radio but the system also needs to reproduce various 5.1 formats from new sources such as DVD, usually for the rear seat. This paper discusses the alternative architecture and processor options and proposes a Logic 7 system, adapted for automotive applications, as an elegant solution, providing enhanced spatial reproduction of 2 channel material and the full surround effect from 5.1 sources.
Paper 5286

12:30 hr A-7
Test Signals for the Objective and Subjective Evaluation of Automotive Audio Systems
Mark Ziemba
Panasonic Automotive, Southfield, MI, USA

Different test signals and test methodologies are used to evaluate automotive sound systems. On the objective side are technical measurements that produce graphical plots of data. In contrast are subjective listening tests that use music as a test signal and yield a psychoacoustics perception from the test subjects. This paper investigates many of these test methodologies and then uses some new test signals for both objective measurement and subjective evaluation of vehicle sound system performance.
Paper 5287


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