Martin Hartung from the IDS German Language Institute in Mannheim knows that a “fried potato affair” was an World War I era tryst that ended because one lover could no longer provide their hungry partner with proper victuals.

Hartung is the keeper of some 15,000 voice recordings at the Archive for Spoken German at the Mannheim institute, where researchers collect audio samples to document changes in the German language. The collection of 4,400 hours of recordings includes rare dialects and interviews with German-speaking emigrants – who keep antiquated expressions alive abroad.

“Our task is not only to collect this cultural-historical documentation. We also pass them along when requested,” Hartung said. “Clubs and museums use the voice recordings for exhibits and parties. Children want to know how their parents used to talk.”

Anyone travelling from the Germany’s North Sea coastline to the Bavarian Alps can tell you German comes still has strong regional flavourings. But the 43-year-old linguist said modern life is making Germans more and more alike – which in turn encourages people to explore their local linguistic heritage.

“While cultural differences are threatening to disappear, interest in dialects is noticeably growing,” Hartung said, adding that the number of inquiries from people from what used to be East Germany had surged in recent years.

Interest in Plattdeutsch, or Low German from the country’s northwest, is also experiencing a considerable revival.

The collection includes a wide array of language samples including the work of archive founder Eberhard Zwirner, who in the 1960s made recordings from more than a thousand different places in the German-speaking world.

“Media, popular culture and historical events constantly change language,” Hartung said, explaining that in the age of globalisation and the internet the use of Anglicisms in German is rapidly increasing. But he said similar developments have taken place before, such as the French influence during the Napoleonic era.

But new technology is also playing a role in the institute’s quest to preserve endangered dialects and expressions like Bratkartoffelverhältnis. With most of the 15,000 recordings on audiotapes, one of the main tasks for Hartung and his 14 colleagues is to digitalise the entire collection. Eventually all will be available to listen to online.