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The Vuvuzela has become the unofficial symbol of the 2010 World Cup - and seems to be loved and hated in equal measure. Here are 10 things you might not know about the tuneless horn.

It is plastic horn, brightly coloured, and seen in abundance at sporting events in South Africa. The first vuvuzelas seen at sporting events in the early 90s were made from a sheet of metal. A standard vuvuzela is 65cm long but some can be up to a metre long.

No-one really knows. The most commonly-held belief is that it is related to the kudu horn that was blown to summon African villagers to meetings.

However, earlier this year, the Nazareth Baptist Church claimed the vuvuzela as its own - used by its members on pilgrimages - and threatened legal action to stop them being used at the World Cup.

Again, it appears to be a matter of debate. Some think it comes from the Zulu word for "making noise". Others say it is township slang for "shower" because it "showers people with music". Many believe it means "pump up".

The Nazarath Baptist Church says it "lost" the vuvuzela back in the 1990s when a supporter of South Africa's biggest football team visited the church. Unable to take the long metal trumpet inside the football grounds, he re-modelled it in plastic.

Vuvuzela-makers say they began to mass-produce the instrument in plastic when the original tin version began to make appearances at games during the 1990s.

The typical pitch of a vuvuzela is said to be B flat below middle C.

On its own, it has been compared unflatteringly to an elephant passing wind. When there is a football terrace full of the instruments, the sound has been likened to a swarm of angry wasps.

Recent tests found noise levels from a vuvuzela, at full volume and when pressed against your ear, equates to 127 decibels.

This is louder than a drum at 122 decibels, a chainsaw at 100 decibels and a referee's whistle at 121.8 decibels.

The Hear the World Foundation - set up by Swiss hearing products group Phonax to raise awareness about hearing loss - has warned that extended exposure to such noise risks permanent hearing loss.

They have been urging fans to use protection, such as ear plugs and ear muffs.

Some South African shopkeepers say they have run out of ear plugs called Vuvu-Stops.

Neil van Schalkwyk of Masincedane Sport - a vuvuzela-maker - says his firm has now produced an instrument that is 20 decibels lower than the older version.

Well, a London doctor is warning that the vuvuzela could also spread colds and flu germs.

Dr Ruth McNerney, of the London School of Hygiene and Tropical Medicine, told The Associated Press that the instrument has the potential to infect those seated near a person blowing a vuvuzela because a "lot of breath goes through" it.

She said a recent study found that aerosols, tiny droplets which can carry flu and cold germs, were formed at the bottom of a vuvuzela after people had blown into them.

Those particles are small enough to stay suspended in the air for hours, and can enter into the airways of a person's lungs, Dr McNerney said.

Several players complained about the vuvuzela when they were first heard during the Confederations Cup last year, a World Cup dress rehearsal.

Dutch coach Bert van Marwijk has banned them from his team's training sessions, and Portugal's Cristiano Ronaldo admitted this week: "It is difficult for anyone on the pitch to concentrate."

Even some fans watching matches on their television have reported having to put the sound on mute to escape the cacophany.

Yes. They've had a ringing endorsement from Fifa President Sepp Blatter who says they will not be banned.

He said on Twitter that "Africa has a different rhythm, a different sound" and it is an important tradition among South African fans that should be celebrated.

England player Jamie Carragher says he will be taking some vuvuzelas home with him. "My kids have been on the phone and they want two. I've got two in my bag already".

On the contrary. Neil van Schalkwyk says his firm has sold 1.5m vuvuzelas in Europe since October and expects sales of up to 20 million rand ($2.6m; £1.7m) over the course of the tournament.

Brandon Bernardo of the vuvuzela.co.za website told Reuters news agency they could churn out at least 10,000 instruments a day. "We're completely sold out," he said.

Furthermore, a Dutch designer firm has released a Vuvuzela 2010 app. According to its website, they have had 750,000 downloads of the application.

Even without the World Cup, South Africa's vuvuzela industry is said to be worth around 50 million rand ($6.45m; £4.4m).