It's the sound of a man slowly dying.
His thin fingers trembling, Mothibedi leans over his simple hot plate and puts a tea kettle on the boil.
The 58-year-old former gold miner looks reduced in his old blue work shirt. It hangs off his bony shoulders as he spreads margarine on a slice of white bread for afternoon tea. He slowly sips it in his barren brick house near an old mine-dump.
"Just listen to my voice," he says, "I have problems with my lungs. I can't even walk fast or far. It is very hard for me."
Mothibedi is stricken with silicosis, an incurable lung condition that affects gold miners in southern Africa.
An incurable burden
Silicosis develops over long periods of time. Fine silica dust lodges deep inside miners' lungs as they extract gold, day after day, year after year.
As the silica particles accumulate, lung function becomes severely limited. The miners have shortness of breath, lose weight, become prone to heart disease and, in the most severe cases, an early death.
Several studies estimate that there are at least two hundred thousand current and former miners in the region suffering from the disease. Researchers have called it a pandemic.
On Friday, thousands of gold miners were given the go ahead to proceed with their landmark class action suit -- the biggest in South Africa
's history -- against mining firms.
South Gauteng High Court Judge Phineas Mojapelo ruled that there is "sufficient common action to satisfy a class action."
"Almost the entire gold mining industry is involved in this case. The scope and magnitude of the proposed silicosis case is unprecedented," said Mojapelo.
The suit, in part backed by prominent U.S. litigation firm Motley Rice, alleges that the companies should have known the harmful effects of silica dust in their mines and didn't do enough to stop it.
The South African Chamber of Mines, which counts several of the defendants in the suit as its members, told CNN that the companies have been working to improve dust management and eliminate silicosis risks and are offering to set up a medical fund for the plaintiffs in the case.
"The companies are all defending themselves in the class action. However, they do recognize that silicosis is a significant legacy issue," says Alan Fine, a spokesman for the industry group.
But Doctor Rhett Kahn doubts the sincerity of those companies. He has treated silicosis patients for decades.
"The companies don't care about the miners, their dust levels are high. I believe they are illegally high," Kahn says. "In a country that is supposed to be the democratic flagship of the world, this is totally unacceptable."
Kahn and his wife Janet run a small general practice clinic in Welkom, a somewhat faded mining town that was once a thriving center of the gold industry that is long past its boom years.
Miners, many too sick to work, come to Kahn's busy practice from around Welkom, but also from neighboring Mozambique and Lesotho to get help. Janet guides them through the maze of medical paperwork. Rhett says they sometimes wait here for days.
A history of neglect?
The history of gold mining in South Africa is one of riches and neglect.
The veins of gold found in the Witwatersrand in the late 1800s sparked a gold rush that transformed the country's largely agricultural economy into an industrial powerhouse. In 1970, more than 20 percent of South Africa's GDP depended on the mining sector, including gold. Lately, its importance is much diminished.
The foundation of South Africa's wealth was built on the backs of black miners. Mining industry segregation was a crucial element in the racist policies that culminated in decades of apartheid rule.
Despite the risks, millions of black migrant workers from rural South Africa and neighboring states flooded the mines as cheap labor.
Until 1993, white miners were paid substantially higher compensation for silicosis-related illnesses. According to researchers like Jock McCulloch, silicosis rates were vastly underestimated among black miners for decades.
McCulloch and other researchers say that the rates haven't got any better since apartheid ended more than twenty years ago.
"It's as bad as it was during apartheid," says Kahn.
How much for a life?
Miners with proven silicosis can apply for compensation from a government fund -- but many die before the complicated paperwork is complete.
Mothibedi says he got a one-time payment of around 5,000 dollars in 2008. It was meant to last him a lifetime. Now, he depends on disability grants.
When Mothibedi grew up in nearby Lesotho, he saw the mines as the only opportunity to further himself.
"When I started to work in the mines I wanted to just make money and go back to school and study," he says. "But when I started seeing people making money I thought I could save money and start my own business."
He slowly moved up to one of the few more senior jobs at the mines that black miners could hope to get during apartheid, all the while sucking in the dust that that would ruin his lungs.
Silicosis put an end to Mothibedi's dreams.
"I feel helpless. This sickness has destroyed everything in my life," he says.