2012 INFINITI M HYBRID FEATURES AUDIBLE PEDESTRIAN WARNING SYSTEM
The new 2012 Infiniti
M35h is not only the first-ever Infiniti Hybrid, it is the word's first hybrid
to feature a standard audible pedestrian warning system. The new Infiniti M
Hybrid is set to go on sale at Infiniti retailers nationwide in early 2011,
following its North American debut at the Los Angeles Auto Show in November.
With its advanced Infiniti Direct Response Hybrid™ system, which includes a
unique 1-motor, 2-clutch, powertrain with compact Lithium-ion battery, the
Infiniti M35h is capable of traveling faster and farther on electric-only mode
than conventional hybrid designs. The new audible warning system, called
Approaching Vehicle Sound for Pedestrians (VSP), uses a range of distinctive
sounds to help ensure the safety of other road users. VSP automatically works
from start-up to approximately 20 miles per hour, cutting back in at
approximately 15 miles per hour as the vehicle slows.
The computer controlled system links an in-car sound synthesizer with a speaker
built in to the front bumper. Instead of just a single tone, a range of
high-low sounds at different volume levels was chosen after an extensive
research program to find the most effective, but least intrusive, noise. The
VSP development team worked with cognitive and acoustic psychologists studying
areas including pedestrian behavioral patterns and noise pollution. The result
is a sine-wave sound that extends from 2.5kHz at the high end to a low of
600Hz. It is a range readily audible to all age groups, while avoiding a sound
range (around 1,000Hz) that would add unnecessary noise to the environment.
The noise sweeps from high to low frequency depending on vehicle speed and
whether the Infiniti M35h is accelerating or decelerating. It is loudest at
start-up to give a clear indication the vehicle is beginning to move off, while
an intermittent tone is used when reversing -- both sounds calculated to ensure
the Infiniti M35h cannot surprise pedestrians and the visually impaired as it
approaches.
Although the Infiniti M35h can travel at speeds of up to 62 miles per hour on
engine noise-free electric power alone, road noise past approximately 20 miles
per hour means the vehicle generates sufficient sound for the VSP to remain
off. An extensive testing program during the hybrid's development showed that,
in mixed driving conditions, the Infiniti M35h was able to drive in
electric-only mode for as much as 50% of the time.
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