vehicle warning sound

Vroom-vroom or tra-la-la? - 'ring tones' for EVs

Pedestrians may be alerted to the approach of an electric car by the sound of the manufacturer's theme tune, if new safety rules come into force.

Electric vehicles, and hybrids running in electric mode, can be near-silent in operation. Japanese guidelines already require vehicles to emit warning sounds, and legislation on minimum sound levels is likely to be introduced in European and North American markets.

To simplify integration of sounder systems into vehicles, Delphi Automotive has developed two single-box sound generators that it describes as environmentally friendly, compact, lightweight and low-cost.

The basic model is approximately three times lighter than a conventional multi-box system and uses 90 per cent less power. Its single-box configuration helps to reduce design, test and manufacturing cost, and its size and weight simplify packaging. The system provides a frequency range of 500Hz to 10kHz and can reproduce melodies that represent the identity of individual vehicle manufacturers.

For applications requiring higher quality sound, a high-fidelity sounder system uses a cone speaker activated by a light-weight magnet that extends the base range to 150Hz, with a weight one-third that of a conventional speaker system.

Both sounders are robust enough to be mounted in the harsh environment under the vehicle's bonnet and incorporate a 32-bit microprocessor with flash memory, a link to the vehicle's data bus and an audio class-D amplifier.

As a system integrator, Delphi can increase the value of the sound generators by connecting them with other systems through the vehicle's data bus. Instead of implementing several alert systems, OEMs can benefit from one flexible system that offers multiple features. For instance, using unique sounds, the system can remind a driver that the battery needs to be charged, confirm that a charging sequence is in progress and notify the driver when the charge is complete.

"Every car has a personality, and we want our customers to be able to choose the system that best represents their brand," said Beth Schwarting, general director of Delphi's electronic controls business.

An unnamed European manufacturer is expected to introduce the first vehicles fitted with Delphi sound generators in 2012.

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