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| TX: 11.05.09 - Silent Cars PRESENTER: PETER WHITE |
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| Downloaded from www.bbc.co.uk/radio4 THE ATTACHED TRANSCRIPT WAS TYPED FROM A RECORDING AND NOT COPIED FROM AN ORIGINAL SCRIPT. BECAUSE OF THE RISK OF MISHEARING AND THE DIFFICULTY IN SOME CASES OF IDENTIFYING INDIVIDUAL SPEAKERS, THE BBC CANNOT VOUCH FOR ITS COMPLETE ACCURACY. WHITE Now here's something you might not know: a normal petrol engined car can be heard about 12 yards away but an electric car can only be heard three yards away and the safety of pedestrians has prompted at least one car manufacturer to develop ways of making electric cars noisier. Carolyn Atkinson has this story. ATKINSON Well Peter those figures you mentioned come from engineers at the University of California and this is what they mean because this is the sound of a standard electric car coming down a standard road. CLIP OF ELECTRIC CAR So not much to hear and if you don't look before you cross the road, and we know children very often don't, or if you're partially sighted or blind, you don't have much time before you get hit. Which is why Lotus has been working on this and it wants a minimum noise level for electric cars because what you're about to hear is the sound of an electric car with an artificial noise synthesiser attached which bumps up the sound of the electric car so that it's easier to hear. CLIP OF MODIFIED ELECTRIC CAR So there's a growing realisation that having a much quieter car may have safety implications. In America a senator there is pushing a bill through at the moment which could create a minimum noise level for cars. Nothing that specific here but the European Commission has told me that they are working on what they call EU type approval for electric vehicles, particularly where safety is concerned and it's launching a study this year which will examine sound levels as well as other safety issues. Over at the UN, as well, they're also looking at technical and standard requirements for cars and vehicles. But the Department of Transport told me there's no evidence that quieter vehicles are actually involved in anymore accidents than noisier vehicles and that if any EU proposal were to be made it would be considered on its merits. This is interestingly all - there is interestingly though already a maximum noise level for cars. And of course driving electric cars could come more popular as the government tries to encourage us all to be less dependent on fossil fuel and to reduce our carbon footprint and already they're exempting electric cars from road tax and from congestion charges. WHITE Carolyn Atkinson, thank you very much indeed. Well on the line from our Norwich studio is Colin Peachey, who's chief engineer at Lotus, where we were hearing about those experiments that are going on. Colin, how does this noise synthesiser actually work? PEACHEY Well what we've basically done is we've captured the main noise frequencies from a standard car as it drives down the road and then we generate these sounds through a speaker right at the front of the car using a synthesiser type technology. WHITE And also I gather the noise varies with what the car happens to be doing? PEACHEY Well that's right. We did some work with the Guide Dogs for the Blind Association who gave us some really good feedback about the sorts of noises that were most recognisable as a vehicle and like an ordinary engine the engine note changes as the car goes faster and slower and also the volume changes with speed as well. WHITE Because obviously a steady speed or a consistent noise wouldn't help here, you have to hear the car changing behaviour? PEACHEY It gives a certain amount of information but if you're unsighted the actual sound that the engine makes tells you how far away the car is and also how fast it's travelling. So there's a lot of information that works on a subjective level for you to interpret these sounds and give you a warning. WHITE Now you say it's in front of the car, what's the significance of that? PEACHEY Well the idea is that the car provides the warning as it's approaching and the sound is all projected in a fairly focused narrow beam forwards. Once the car's actually gone past it's just the sound of a normal electric hybrid vehicle, i.e. you can't hear it. But the other thing is that the sound is kept quite low and quite restricted in its beam so that if you're say upstairs in a bedroom at night and the car drives past you would hear an ordinary vehicle but our electric vehicle with this synthesised sound you wouldn't hear that because the sound is quite dedicated and focused in a particular area. WHITE So you can't hear it or not as much anyway when it's gone past you either, it's only when it's - when you're in front of it if you like? PEACHEY That's right. The sounds - we're quite conscious we don't want to add to noise pollution, so we're really providing the right sort of sound, the right sort of level just to provide a warning. WHITE Now a lot of people say the noise - the noise comes from the tyres, so how much from the tyres and how much from the car itself? PEACHEY Well that does depend upon how fast the vehicle's going. At low speeds, below say 20 miles an hour, the tyres don't make that much sound, at higher speeds the tyres become more dominant. And so our system, because it words on the vehicle speed as one of the inputs, it can actually switch off once the tyre noise becomes greater and takes over as the main warning. WHITE It does seem very counterintuitive though - making cars noisier. I mean why should the government legislate for a minimum noise requirement when they say that there isn't any evidence that there are more accidents with quieter cars? PEACHEY Well there haven't been any reported deaths or major injuries due to these cars but when we started working on electric and hybrid cars at Lotus we did find that just moving around the factory people would step out in front of them and you can speak to quite a lot of people and there are a lot of anecdotal stories about very near misses and minor accidents, the sort of thing in a car park where someone gets a minor knock because the car has reversed out and they didn't hear it, probably doesn't get reported. WHITE Colin Peachey of Lotus thank you very much indeed. Back to the You and Yours homepage The BBC is not responsible for external websites |
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