'Sound' Engineering Solution at Siemens VDO Automotive

       Siemens VDO Automotive Develops Active Noise Control For Engines

    FRANKFURT, Germany, Sept. 13 Particularly at low speeds,
the sound level in a car is dominated by the noise created by the engine as it
draws in fresh air.  Siemens VDO Automotive is contributing to improved
acoustic comfort and performance with its Active Noise Control (ANC) system
for engines being presented at the 59th Frankfurt Motor Show.

    The "breathing" of the engine is particularly noticeable during hard
acceleration from low speed.  In order to eliminate this air intake noise,
Siemens VDO Automotive applies a technique of simple physics: Two waves of the
same amplitude, but opposite phase, cancel one another out.  A noise
consequently can be overlaid or positively changed by an opposing noise of the
same volume.  It is important that the original and secondary noise sources be
kept close together.

    In the Active Noise Control (ANC) system from Siemens VDO Automotive a
loudspeaker installed in the intake system is used to generate opposing noise.
The power consumption of the loudspeaker in the relevant engine speed range is
limited to a few watts.  A microphone on the air intake side continuously
monitors the noise level.  The system is controlled by electronics also
installed in the intake system.

    With individual frequencies being suppressed and others amplified, ANC
gives the automobile manufacturer greater freedom in engine noise design.
Selective sound design can be used to adapt the noise behavior of an engine to
the character and marketing strategy of a particular car model.  In the
frequency range up to 600 Hertz, Siemens VDO Automotive has demonstrated a
significant improvement in the vehicle acoustic performance, a major factor in
overall driver satisfaction.

    ANC has been successfully tested by Siemens VDO Automotive on various
engines on the test benches and in practical operation.  The Air Fuel Modules
division is continuing to develop the system in Windsor, Ontario, Canada.
Siemens VDO Automotive is scheduled to be ready for the start of production
with ANC by the year 2005.

    Siemens VDO Automotive is one of the world's leading suppliers of
electronics, electrical and mechatronic technologies to the automotive
industry.  As a development partner in the automotive industry, the company
manufactures products for powertrain, engine control electronics and fuel
injection technology which improve engine performance and reduce emissions.
The company is a market leader in information and car communication systems
with instrumentation, audio and navigation systems, telematics and multimedia
applications, through to complete cockpits.  Siemens VDO Automotive products
for chassis and carbody contribute to greater vehicle safety and security.
These products include ABS and fuel tank systems and access control systems.
A separate Trading/After Market division markets products for retrofitting in
cars and commercial vehicles.  The company was created in April 2001 as a
result of the merger between Siemens Automotive and Mannesmann VDO.

    The company's parent organization, Siemens AG, is headquartered in Berlin
and Munich and is a leading global electronics and engineering company,
employing over 447,000 people in 193 countries, with worldwide sales in excess
of $74 billion in fiscal 2000 (10/1/99 - 9/30/00).  The United States is
Siemens' largest market, where it employs over 73,000 and recorded sales of
more than $17 billion in fiscal 2000.