Professor Ammon found that German is only ranked tenth globally in terms of native speakers, of which there are around 104 million, but is ranked fourth in terms of non-native speakers who have learnt the language.
The only larger languages in terms of learners are English, French and Mandarin, he told Deutsch Welle.
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"People get the impression that when you learn German, you are gaining access to countries that are flourishing economically, which in turn brings better career opportunities as well as education and training." he said
"The association between German and economic prosperity is nothing new and dates back to German unification in 1871," he later told The Local.
But Germany's recent role in the Eurozone crisis has also contributed to German's attractiveness.
Viola Noll, a spokesperson for Goethe Institute, said that the Eurozone crisis had led to a boom in southern Europeans wanting to learn German, mainly Spaniards, Italians and Greeks.
Around 14.5 million people worldwide are learning German as a foreign language, according to the latest estimates from the Goethe Institute. It is taught in schools in 144 countries around the world.
Mark Twain famously said that German was too hard to learn in one lifetime, but Professor Ammon thinks the difficulties in German are exaggerated.
"The grammatical structure in German is perhaps more difficult than other major European languages, but as soon as a language is considered useful, people forget about the difficulty," he said.
Currently more people are learning German than Spanish, despite the enormous number of Spanish native speakers around the world. Professor Ammon can see this continuing in the future:
"German will never challenge English, which is the truly international language, but prosperity can continue to make a difference, particularly if Spain continues to struggle economically" he said.
What people associate with German
Another element of Professor Ammon's study is the associations that non-German speakers make with the language.
For example, businesses in non-German speaking countries sometimes use German in branding or marketing to seem more official, professional, or successful.
"Businesses do it because German is associated with higher quality" he said in an interview in Welt
Examples of this would be the use of German in the Audi slogan "Vorsprung durch Technik" (Advancement through technology) in adverts around the world to convey the quality of German engineering - although the notoriously language-shy Americans have to make do with "Truth in Engineering".
"Whereas English stands for internationalism, other languages have other special qualities that fit to the stereotype associated with the language speaking community.
"In the case of German, these are hard work, order, and coziness" he said.
"It is clear that people who have learnt a foreign language more often than not have a positive attitude towards that country. For international relations that is really important" he added.
But most people generally aren't aware of how popular their language is and of the advantages this brings, such as easier global communication which is better for international business, he told The Local.
Head of the culture department of the foreign office in the 1980s, Bethold C. Witte, once said: "Wer Deutsch spricht, kauft auch Deutsch" (Whoever speaks German will also buy German).
A bright future?
Despite German's healthy standing, Professor Ammon still believes that more can be done.
He would like to see more use of German in public, particularly on the European political scene where English and French dominate, as well as grants for foreign students to learn German, but acknowledged that funding will always be an issue.
When asked if German was held back by the fact that Germans tend to have a good level of English, Professor Ammon suggested that his countrymen are prouder of their ability to speak foreign languages than of their own language.
He put this down to Germany's "broken national identity", which means they aren't as proud of their language as other nations such as the French.
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He gave the example of a group of English children who visited a school in the Rhineland.
They took part in the exchange to improve their German, but to the German head teacher's delight, the two groups communicated with each other in English.
He highlighted this as an area where Germans could actually promote their mother tongue. Instead of showing off their own language skills, they should realise when others want to learn German and embrace it.
He also added that: "Although Germans generally speak English well, they could do better in this regard, like the Dutch or the Scandinavians."
Germany is ranked as the tenth best country in the world for English proficiency, which means it comes above other major European nations like France, Spain and Italy, but still lags behind many northern European countries.