Michael Wu, 20, a student at Peking University, grew up in Shanghai. But when he wants to talk to his cousins in Hainan, he needs to bring his mother along to interpret the conversation.

The cousins in Hainan speak two kinds of Hainan dialect. "I actually cannot understand either of them," Wu says. "It's actually not much good for me to [try to] communicate with them."

In China, that's a common problem: The differences in dialects are so vast they amount to different languages—possibly more than 3,000 variations, according to some estimates. It's one of the reasons that standard Beijing Mandarin has become the lingua franca of schools, businesses and government in China. But that uniformity comes at a cost: the rapid loss of many of these dialects.

A screen shot from the Phonemica home page. Phonemica

Now two Americans have taken on a daunting task: trying to get an audio record of all of the thousands of China's languages and dialects before they disappear.

Linguists Steve Hansen and Kellen Parker are enlisting volunteers to canvass the country to capture both the languages and the stories of all of China's 2,862 counties and 34 provincial areas. Phonemica, founded last year, now has about 200 Chinese and Chinese-speaking foreign volunteers lined up to record their friends, parents and grandparents, telling a story in fangyan (regional speech).

"The idea is that we want to record it all," says Mr. Hansen. "And the only way to do this is through a crowd-sourced approach. We're trying to get people involved who will go to their hometowns and record friends and relatives."

"It is absolutely unique," said Victor Mair, a professor of Chinese language and literature at the University of Pennsylvania, by email. "No one else is attempting to do this for Sinitic" (the languages of China).

Phonemica is nearly out of time. Scholars say that a few generations from now, all of China will speak as a first language standard Mandarin, the Beijing dialect that is taught in schools and used by new migrants to cities as well as businesspeople in every province.

Richard VanNess Simmons, a Rutgers professor of Chinese, says that as China's economy has taken off over the past 20 years, "Mandarin has become the language that gets you somewhere and the language that parents want their kids to learn." Even parents who speak regional dialects prefer that their children speak Mandarin at home.

"It's happening so fast it's almost too fast to document," he says.

The Chinese government also has taken on the task of recording the country's dialects, but its Chinese Language Resource Audio Database (中国语言资源有声数据) is still in the "fieldwork" stage, says Mr. Simmons, and "no results have yet been published as far as I know."

Click here to listen to recordings from the Phonemica project.

An earlier effort by the Chinese Academy of Science in the 1990s, he says, produced a small series of about 20 recordings of dialects on audiotape and in book form. The academy then put out a DVD version that required users to install an old browser for Windows, so "it didn't end up being very useful in digital form."

Virtually unlimited storage in the era of cloud computing means Phonemica can record as many dialects as it wants without worry about technology becoming obsolete. The bigger challenge has been in getting drumming up enough volunteers to make recordings.

The site's original model was the Speech Accent Archive created by George Mason University in Virginia, which records hundreds of English speakers reading the same English-language paragraph with different accents, from Brooklynese to Dutch. But Messrs. Hansen and Parker felt that there was also value in recording family stories, in the style of StoryCorps, an archive of 45,000 stories told by Americans to each other.

So far, the site has 50 stories on record, ranging from young people talking about their favorite Chinese pop stars to grandparents remembering being sent to work in the countryside during the Cultural Revolution. Mr. Hsieh, a 61-year-old from Pingtung County, Taiwan, tells a story in the Hakka Sixian dialect. There are more than 30 million native speakers of Hakka, Mr. Parker says, but the Sixian dialect group is much smaller, mostly in the northwest part of Taiwan. Song Hongcheng, 50, from Fangxian in Hubei province, tells a story in the Fangzian dialect, a subset of Central Plains Mandarin, which has about 300,000 speakers.

So far the project has relied too heavily on young people—students interviewing fellow students—with not enough contribution from older generations, according to Mr. Simmons, who serves as an informal adviser to the project. He advised Phonemica to try to record people over the age of 30, and preferably over 60. Younger people, even if they speak in a dialect, tend to throw in standard Mandarin words more often than their grandparents would.

Leonardo Liu, 40, who has already recorded his parents, his wife and several colleagues, says the project made him wonder what it would have been like to hear the voice of Confucius. "Maybe 1,000 or 2,000 years later, we'll be the ancient people. If the website can keep our voices and our accent, it will be great."

—Debra Bruno