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Each city has its own distinctive soundscape, from birds and radios to trains and ambulances. For Delhi residents the backdrop of rush-hour traffic is causing noise pollution so serious that experts are warning of serious health consequences.

I am lucky to live on a cul-de-sac in New Delhi. My day begins with green parakeets squawking as they play in the trees. A temple bell chimes. A fruit seller rolls his pushcart past, shouting: "Custard apples, guavas, papaya!"

I miss these sounds when I wake up in London, where it often feels as quiet as a morgue. But for most Delhi residents, these pleasant sounds are drowned out each day by the traffic roaring past their homes.

Seven million cars - more than in India's three other major cities combined - jostle for space on Delhi's roads. Besides the revving of engines and squealing of brakes, ear drums are hammered by the continuous blast of automobile horns.

At intersections, impatient drivers eager to turn right use all lanes, blocking those wishing to go straight, naturally instigating loud outbursts of anger.

Instead of slowing down while turning or approaching an intersection, drivers will blast their horns to warn others of their presence. They also honk at cyclists, pedestrians, children, pye dogs, cows and anyone else unfortunate enough to be slower than them.

Less than a split second after a traffic signal turns green, the assault begins afresh, as if the sheer force of the decibel level will push cars forward.

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Often, the smallest vehicles are the noisiest. Kamikaze motorbikes and scooters weave dangerously through traffic, popping out unexpectedly from your blind spot as they emit a violent buzz. After dark, the pressurised air-horns of lorries blast their strident musical tunes as they race down empty roads closed to them during the day.

Millions of vehicle horns are bad enough, but then consider that they are drastically louder than the ones sold in Europe or the US.

I went in search of the horn bazaar in Old Delhi one day. Amid the crumbling facades of 16th Century havelis [mansions], I found the oddest assortment of car parts for sale - metal suspension springs as tall as busses, mountains of spare headlights, wing mirrors, seats and even whole chassis blocked the pavement.

One street was dedicated entirely to horns.

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I found a shop where the keeper proudly displayed a large selection. I asked which was the loudest. He pressed a buzzer - without warning. My eardrums felt pierced by the blast. I staggered backwards, covering my ears, astonished at how a sound could physically hurt.

At 118 decibels, it was equivalent to a thunderclap. My ears throbbed for two days.

And yet, the shopkeeper explained, drivers come especially to replace their in-built horns with these much louder ones.

"People here just will not move out of the way unless you have a really loud horn," he said.

Honking is illegal near schools, hospitals and at intersections in Delhi but hardly anyone complies.

As a result noise pollution has become so intense it is having a measurable impact on people's health.

A recent study showed not only is it affecting school children and hospital patients, it is contributing to increased stress and heart disease, and causing the onset of age-related deafness 15 years earlier than normal.

The problem is so bad one man is resorting to guerrilla tactics to educate drivers.

For the past five years Delhi resident Ravi Kalra and his band of volunteers have been stopping traffic, lecturing drivers, and slapping their cars with stickers that say: "Do not honk!".

The morning I visit him, people honk at the volunteers for causing delays. He says he often gets dirty looks, even curses, but wants to prove that Indians can be considerate drivers.

Watching him, I realise honking is just the symptom of a corrupt system in which most drivers can buy a licence without ever learning the rules of the road.

Imagine if London was filled with discourteous learner drivers unafraid of the inept police force.

Imagine they straddled lanes, drove with wing mirrors folded in, braked suddenly to answer mobile phones in dangerous conditions, decided to back up against oncoming traffic, and you have an idea of what it is like to drive in Delhi.

The result is chaos and road rage so potent that I am sometimes surprised people stick to the non-lethal option of the horn.

As I watch Ravi Kalra talk to Delhi drivers, it is clear his advice is often going in one ear and out the other.

Perhaps all that honking has already made drivers deaf to common sense.

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