2012 Infiniti M35h Has Vehicle Sound for Pedestrians

Infiniti's first ever hybrid, the new 2012 Infiniti M35h, is the world's first hybrid to feature a standard audible pedestrian warning system. It had just been released to the North American market this week and will hit dealerships in early 2011.

The unique Infiniti Direct Response Hybrid system makes use of a unique one motor, 2 clutch powertrain with compact Lithium-Ion battery, and it is capable of traveling faster and farther on electric-only mode than ordinary hybrid designs.

The vehicle can run on electricity alone up to 62 mph (100 km/h), emitting almost no noise whatsoever. So engineers at Infiniti found a solution to alert pedestrians of incoming traffic, in the form of an audible warning system, called Approaching Vehicle Sound for Pedestrians (VSP), that uses a range of distinctive sounds to help ensure the safety of other road users.

The VSP works from start-up to about 20 mph, and goes back in effect at approximately 15 mph when slowing down. The system comprises of a computer-controlled sound synthesizer that transmits through a speaker incorporated in the front bumper. Instead of using a single tone, the system emits a range of high-low sounds at different volume levels, that are the least intrusive, yet effective. The VSP development had studied pedestrians' behavior thoroughly and chose a sound with the least environmental impact, but readily audible to all age groups.

The noise ranges from high to low frequency, and is correlated with the vehicle's speed and whether it's accelerating or decelerating. At start-up, it emits a loud tone to give a clear warning that the vehicle is moving off, while reversing is signaled by an intermittent tone.

Although the Infiniti M35h can travel a lot faster than 20 mph on engine noise-free electric power alone, the car generates enough road noise past the 20 mph mark, so that the VSP can be turned off. Extensive testing in mixed condition showed that the M35h could only travel all-electric for as much as half of the time.