The Infiniti M35h will become the world’s first hybrid to feature an audible pedestrian warning system as standard when it goes on sale in six months’ time.
The high performance hybrid model utilises a range of distinctive sounds to help ensure the safety of other road users.
The new Approaching Vehicle Sound for Pedestrians (VSP) system is computer controlled and links an in-car sound synthesiser with a speaker built in to the front bumper. It automatically works from start-up to 30 km/h, cutting back in at 25 km/h as the vehicle slows.
Instead of just a single tone, a range of high-low sounds at different volume levels was chosen after a research programme to find the most effective, but least intrusive, noise. The team developing the system in Infiniti’s parent group worked with cognitive and acoustic psychologists studying areas from pedestrian behavioural patterns to 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 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 M35h cannot surprise pedestrians and the visually impaired as it approaches.
Although the M35h can travel at speeds of around 80 km/h on engine noise-free electric power alone, road noise past 30 km/h means the M35h generates sufficient sound for the Approaching Vehicle Sound for Pedestrians to remain off. A testing programme during the hybrid’s development showed that, in mixed driving conditions, the M35h was able to drive in electric-only mode for as much as 50% of the time.
Approaching Vehicle Sound for Pedestrians will come ready installed on every M35h in Europe when sales commence from spring 2011 (depending on country). Approaching Vehicle Sound for Pedestrians joins a host of safety systems available on the M35h including the Dynamic Safety Shield, standard on Premium versions.
The M35h is the first model from Japan’s newest luxury automotive manufacturer to feature Infiniti Direct Response Hybrid technology. Combining a 306 PS (225 kW) 3.5-litre petrol V6 with a 68 PS (50 kW) electric motor, the M35h delivers sports car performance alongside an ability to glide on zero-emissions electric propulsion – more often, for longer periods and at higher speeds than in existing hybrids.
The surprising result for the driver of the M35h is 0-100 km/h in under 5.9 seconds and combined fuel consumption of 7.3 l/100 km (both figures subject to final homologation), making it Infiniti’s fastest as well as cleanest and greenest model.