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
