A handful of fed-up residents in one of the world's noisiest cities have taken on a daunting challenge: persuading Indian drivers to stop honking their car horns.
Non-stop beeping has become the dominant soundtrack to Mumbai as clattering rickshaws, buses, clapped-out taxis, weaving motorbikes and private cars fight for space on the traffic-clogged roads.
Now two separate teams in the city have come up with devices aimed at instilling some peace: one by fining overzealous horn-users and another by appealing to drivers' consciences.
"People blow their horns just for no sake," says Jayraj Salgaonkar, who with a group of engineers has developed the "Oren horn usage meter" (the name "Oren" derives from local pronunciation of the word "horn").
The meter allows for a limited amount of honking, after which it causes the vehicle's tail lights to flash and alert traffic police, who could then fine the driver.
The driver gets green, amber and red-light warnings over his honk allowance and can top up his meter "like a pre-paid phone card", Salgaonkar says. He wants the device mandated city-wide.
"I have invested money and time and emotion," he said, relating his years of exasperation with the city's cacophony. People take pride in honking their horn. There's an ego trip over having a car. Until you make people pay for their usage of the horn it's not going to work," said the publisher turned honk activist, who is hoping that the potential revenues brought by the system will help persuade authorities to adopt it.
The second invention, also vying for official sanction, is called Project Bleep. A little red button on the dashboard beeps and flashes with a frowning face, "to make the driver conscious that he just honked and make him deliberate why he did it," said Mayur Tekchandaney, one of its creators. "Mostly it's habitual. The driver doesn't realise he's doing it."
After testing the device on 30 drivers over six months, Tekchandaney and his team at Mumbai design firm Briefcase found an average 61 per cent reduction in honking.
"The benefit is to other people on the road, society in general," Tekchandaney said. "It creates a nuisance for the driver."
Their goal may sound ambitious in a country where honking is so pervasive that foreign carmakers, including Audi and Volkswagen, fit their Indian vehicles with stronger, longer-life horns.
Nationwide, the messages "Horn OK Please" or "Blow Horn" are colourfully painted on the back of most trucks and lorries, encouraging drivers to make their presence audibly known as they overtake.
And the noise is only set to increase as more vehicles pile into densely-packed Mumbai, where the middle-class is growing and whose shoddy infrastructure and crowded trains do little to encourage the use of public transport.
There are now about 900,000 cars, 10,000 buses and two million two-wheelers plying the roads of the financial capital with a population of 12 million.
Anti-noise crusaders say that honking is taking a worrying toll on the health of Indian city dwellers - especially when combined with construction projects, roadworks and religious festivals celebrated with ear-splitting firecrackers.
Sumaira Abdulali, founder of the Awaaz Foundation, which campaigns against noise pollution, said sound levels in busy parts of Mumbai continuously exceed 85 decibels, breaking the limits recommended by health experts and contributing to high blood pressure, hearing loss and heart disease.
Mumbai residents are not alone in their quest for a quieter life. In the capital New Delhi, a group of campaigners take to the streets several times a month, plastering cars with "Do Not Honk" stickers. In southern Bangalore, residents launched an "I Won't Honk Campaign", backed by cricketer Rahul Dravid, which aimed to get drivers pledging not to use their horns unless completely necessary.
"Most people say there is excess honking but they think it's the other drivers," says Ram Prasad at Final Mile, a behavioural research group in Mumbai that has examined the honking phenomenon.
Prasad also said that traffic police fines may only encourage bribing, giving drivers the feeling that "they have only extra licence to blow and honk. Any device that gives subtle feedback, people will be more willing to take."