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Research Indicates Engine Sound Significantly Influences Driving Enjoyment and Comfort Levels

VIENNA, Austria, April 25 Siemens VDO Automotive is revealing its acoustic research findings during the 23rd International Vienna Motor Symposium, demonstrating active control of engine sound significantly influences the driver's enjoyment and comfort levels.

Made possible by the company's Active Noise Control (ANC) technology, selective sound design research has identified what engine frequencies increase driving enjoyment levels. Automobile manufacturers wishing to identify both desirable and undesirable engine sounds are increasingly monitoring the relatively new acoustic field of scientific study.

``For example, preliminary studies show low and constant sound levels are not always preferred,'' said Siemens VDO Automotive Project Manager Dr. Marcus Lewis. ``Harmonious sequences of tones are particularly popular. In fact, motorists make similarly high demands on a good engine sound as they do on a symphony.''

Since even the best designed engines cannot completely eliminate resonance, Siemens VDO Automotive has developed the ANC technology allowing engine sound to be actively influenced at its source by utilizing a loudspeaker installed in the air intake system to generate opposing frequencies.

``The system works off the physical phenomenon of interference,'' explained Lewis. ``When two sound waves meet, their amplitudes are superimposed on one another. A new tone is generated with a different volume. In some cases, the waves cancel one another out completely, creating silence.''

North American ANC field tests conducted by Siemens VDO Automotive also have indicated that most drivers only prefer silence when engaged in vehicle operation situations requiring increased concentration, such as at night or during inclement weather. However, harmonious tone sequences seem to be favored during daytime leisure driving, while harmonics emphasizing the acceleration phases are preferred during in-town driving.

In addition to a speaker, the patented ANC concept utilizes a microphone also mounted in the air intake system to continuously monitor and measure sound levels at driving situation-related setpoints. An electronic controller calculates the corresponding tone sequence, which is delivered into the intake system by the speaker.

The entire ANC system only requires a few watts to operate, due to its close proximity to the sound source.

The ANC approach allows automobile manufacturers to more freely manipulate and design engine sound to match the character or branding of a vehicle model or platform. It also increases the rated output of an engine by eliminating the need for passive filters and resonators that hinder the flow of natural air intake.

Siemens VDO Automotive is a tier-one supplier of automotive electronic/electrical systems and components with applications covering gasoline and diesel powertrain systems, safety and chassis systems, body electronics and interior and infotainment. Worldwide sales reflecting partial fiscal year 2000/2001 totaled $5.0 billion.

On January 1, 2002, Siemens Automotive Corp. and VDO North America merged to form Siemens VDO Automotive in the United States. Additional information can be found on the company's web site at .

Siemens AG headquartered in Munich, is a leading global electronics and engineering company. It employs more than 450,000 people in 193 countries and reported worldwide sales in excess of $72.7 billion in fiscal 2001 (10/1/00 - 9/30/01).

The United States is Siemens' largest market, with 77,000 employees and sales of more than $18.9 billion in fiscal 2001. Siemens is a leading provider of advanced technology solutions in the information and communications, medical, power, automation and control, transportation and lighting sectors, and leverages its global network of innovation and unparalleled technological heritage to deliver business results for Siemens' customers around the globe. For more information about Siemens in the U.S., go to