Nissan gets vocal with electric Leaf

NISSAN says its groundbreaking Leaf will not only be the world’s first mass-market electric vehicle, but also the first car to come with a computer-generated engine sound system to warn pedestrians of its approach.

The artificial external noise device was revealed on day one of a week-long Leaf taste test by nearly 500 journalists, Nissan shareholders, government officials and some of the first customers at Nissan’s Oppama test track in Japan from June 11.

Nissan’s Approaching Vehicle Sound for Pedestrians system will be welcomed by advocates for pedestrians and the blind, who have called for audible alert systems for EVs for years, but also means the Leaf – and potentially a host of new EVs that will follow it – will no longer be whisper-quiet.

However, Nissan says the synthesised vehicle noise technology, which will be fitted as standard on the Leaf – including the first pre-production vehicles now being evaluated – will still help reduce noise pollution in cities when it is released in Japan and the US in December, and in Australia in 2012.

“Nissan believes the 100 per cent electric Nissan Leaf has the potential to be the transformative beginning of a new approach to personal transportation. No tailpipe emissions from this global vehicle mean no CO2 or other gases released into the atmosphere,” it says.

“In addition to reducing air pollution, Nissan Leaf and other electric vehicles (EVs) reduce noise pollution, making them transformative in yet another way. Unlike their gasoline-powered cars, EVs and hybrids run quietly. Today’s noisy traffic corridors have the potential to possess an almost serene ambience if populated with cars and trucks that are quieter.

“While silence is golden, it does present practical challenges. In response to public concern that quiet EVs and hybrids can surprise pedestrians and the visually impaired as they approach, Nissan has developed a set of distinctive sounds that will come as standard with Nissan Leaf to ensure a positive experience for drivers, passengers and pedestrians alike.”

Nissan says the Leaf’s audio-alert system, which will also be fitted as standard on the brand’s Fuga (Infiniti M37) hybrid when it goes on sale in Japan this year, makes it easy for those outside to hear the vehicle approaching, but does not distract occupants of the Leaf.

The company said it studied behavioral research of the visually impaired and worked with cognitive and acoustic psychologists to develop the engine noise simulator, which is the first of its type to be introduced by a car-maker anywhere in the world.

Nissan flagged its intention to introduce a high-pitched science fiction sound system for the Leaf last September – a month after the car’s debut at the company’s new global headquarters at Yokohama - when it presented the technology to the US National Highway Traffic Safety Administration.

“We decided that if we’re going to do this, if we have to make sound, then we’re going to make it beautiful and futuristic,” Nissan’s noise and vibration expert Toshiyuki Tabata told Bloomberg at the time. “We wanted something a bit different, something closer to the world of art.” In Nissan’s case, the relatively simple Leaf system consists of a synthesizer on the dashboard and a speaker under the bonnet, which is loudest when the car moves off and switches off completely when the car reaches 30km/h and tyre and wind noise become the dominant sounds.

Producing a high-low “sine wave” of sound that ranges between a high of 2.5kHz and a low of 600Hz to make it audible to people of all ages, the system automatically switches back on at speeds under 25km/h and makes different sounds when accelerating and decelerating.

When reversing, it beeps like the reversing chime heard on trucks and some other vehicles, but Nissan says it avoided producing a sound range of around 1000Hz, which would have added unnecessary noise to the environment.

The system can be switched off, but automatically turns on at start-up in the same way that electronic stability control systems do.

Nissan says the Leaf’s AVSP system, which has been in development for three years, conforms to guidelines set by the Japanese transport ministry report Measures for dealing with the silence of hybrids and similar cars released in January, including that such systems cannot be mistaken for a car horn.

The Japanese government’s EV noise guidelines were established by a committee formed last July, following a request by the Japan Federation of the Blind for the government and car-makers to consider the issue earlier this year.

Japan will be the first nation to mandate artificial vehicle noise for all EVs and hybrids running in EV mode from 2012, while US and EU transport regulators are now considering following suit.

Just as regulators attempt to adopt procedures for measuring the energy consumption of electric vehicles, noise simulators could be also mandated by type approval standards for EVs now being developed in Australia.

When hybrids starting taking off in North America in 2007, the country’s National Federation of the Blind called on car-makers to set minimum sound standards for hybrids, following a case in which a US pedestrian successfully sued for damages after being struck down by a Prius driving in EV mode.

It has been reported that Toyota, which is currently conducting field trials of its next-generation Prius plug-in hybrid, could introduce sound alert devices as early as next year, which may employ radar technology to recognise the presence of pedestrians.

Nissan says it has developed a number of refinements for the production version of its mould-breaking battery-powered car since it was first revealed last year, but it isn’t the first to create artificial engine sounds.

British sportscar maker Lotus developed a petrol engine-mimicking system dubbed ‘Safe and Sound’ in 2008, while Japan’s largest newspaper Yomiuri Shimbun has reported that Toyota and Fujitsu Ten would experiment with various simulated sound vehicle sounds to find “the right tune at the right volume so people are alerted but don't find the sound annoying”.

For about $150, Tokyo-based company Data System Co already offers an aftermarket device that emits 16 different sounds, including a cat’s meow, a ‘boing’ and a human voice saying “excuse me”, and some day a range of “vroom tones” could become downloadable from the internet in the same way as mobile phone ring tones.