Kenneth Feith, who is from a UN group trying cut vehicle noise for over 30 years, admitted it was quite a surprise when he got a request for electric and hybrid cars to make more noise.
"My response was, 'you're crazy'," he recounted.
But as he was taken through the issue of cars so silent that they creep up unnoticed on the visually impaired, elderly and cyclists, the chairman of the UN working group on quiet road transport vehicles acknowledged: "Clearly, there is a problem."
To combat this safety issue, Feith and his team began in March 2009 to work towards creating a new noise standard for electric and hybrid vehicles, which hum almost soundlessly compared to regular petrol or diesel cars.
A US Department of Transportation study found that the rate of accidents involving hybrid electric vehicles was twice as high as normal cars in certain situations, such as when reversing and entering or leaving a parking space.
"Cars have become dangerously quiet," said John Pare Junior, executive director for strategic initiatives at the US National Federation of the Blind.
"This is a big concern for all pedestrians throughout the world, particularly blind people, who can't see cars but can hear cars. We rely on the sound of the vehicles to travel safely," he added.
The UN group is now trying to establish the volume of sound needed, whether a reversing car should emit a different sound, or if a particular sound is necessary when the vehicle is stationary even if its engine is on.
This does not necessary mean creating more noise, said Feith, noting that what is required is a distinctive sound signalling the arrival or a presence of a vehicle.
"We think we can do that without increasing the noise impact overall," he said, noting for example that a ticking sound could be introduced when a vehicle is accelerating.
As hybrid vehicles gain traction with the public, a global norm is needed urgently, said Feith.
Japanese car manufacturers, including Mitsubishi and Nissan, are working on developing systems to make their hybrid cars a little noisier. Toyota is already offering such a system to customers.
To avoid a situation in which each brand comes up with their own types of sounds to signal different situations, the UN working group, which includes major car manufacturing countries - the United States, European Union and Japan, is aiming to come up with a global standard in coming months.
It expects to complete its work in the next one and a half years.
The finalised standard should include specifications on areas such as sound spectrum, sound limits and the detectability of the vehicle over a certain distance.
"We had a car that makes a certain sound and we had to make it quiet. That's a lot harder. Here is a vehicle that starts out being quiet and we just have to make it detectable," said Feith.