At the World Summit on Sustainable Development in Johannesburg, South Africa, grassroots environmental activists complain that their voices are not being heard. To drive that point home, one group, Friends of the Earth International, has created a massive sculpture less than 200 meters from the conference center. The protest artwork features the sounds of nature and the often unheard voices of people around the world.

As you approach the sculpture, you hear sounds that seem out of place in the concrete jungle of Sandton, the luxury suburb where the summit is taking place. The calls of birds and monkeys echo from the sides of tall office buildings, hotels, shopping malls and the shiny Sandton Convention Center.

"I am Emmy from Indonesia. The noise I want to send to the summit is ... the sound of the Sumatran gibbon. They cannot live without trees. So those trees and that forest is disappearing, right now. That's why it is so important to send this message to the summit."

The sculpture is called "Hear Our Voice." Friends of the Earth International wants to remind delegates at the summit why they are here: to fight global poverty while saving the planet.

"I am Andreo from Brazil, and the sound I want to send to the earth summit is ... the sound used by the Chicona people to communicate in the Amazon forest."

Sounds and voices are only a part of the protest sculpture. In the center of a small open area, just down the street from the convention center, stands a giant metal robot. It has glowing eyes, and its head moves from side to side. Friends of the Earth Vice-Chairman Tony Juniper calls it the "corporate giant," symbolizing the power and influence of big multi-national corporations.

"Around the giant, who towers over the sculpture, we have thousands of figures representing the excluded voices of the earth summit," he said. "These figures are made of papier-mache, and they were made in the townships and squatter camps around Johannesburg by ordinary people who again, whose voice is not being heard at this summit, we believe."

There are 6,000 small paper-mache figures surrounding the "corporate giant," one for every million people in the world.

Visitors who stop to inspect the sculpture hear the sounds of nature, combined with the voices of people from all over the world. Over the last few months, Friends of the Earth asked them to "send a sound to the summit."

"My name is Bobby. I'm from South Durban, South Africa. And the noise I'd like to send to the world summit is ... the noise of escaping gas from petrochemical plants, such as Mobil and Shell that are in our communities in south Durban where I live, the noise of escaping gas that could be the death of us."

The sculpture will remain in place until the end of the summit. Afterward, the papier-mache figures will be recycled, and the "corporate giant" will go to the headquarters of a local environmental activist group.