It is one of the most annoying words in the English language and it seems there is no escaping it. The word "huh?" is in worldwide use, a study found. Researchers discovered that languages spoken in countries from Ghana and Laos to Iceland and Italy all include "huh?", or something that sounds very like it. They said that while the study may sound silly, the word is an absolutely necessary part of speech. Without it and similar words, it would be impossible to show that we haven't heard or understood what had been said and this would lead to constant misunderstandings. But while other words used in the same context, such as "sorry" or "what", vary widely across languages, "huh?" remains unchanged. The Dutch researchers carefully studied ten languages from around the world, including Siwu, which is spoken in Ghana, and an Australian Aboriginal language, as well as Italian, Spanish, Dutch and Mandarin Chinese. They analysed tapes of recorded conversations for words that sounded like "huh?" and were used to request that whatever had just been said be repeated. All contained a version of "huh?". The word was also found in another 21 languages. While there were subtle differences in each country, all sounded basically the same. This is surprising because normally unrelated languages will use very different words to describe the same thing. For instance, the Japanese for "dog" is "inu", while the French is "chien". It is thought that languages around the world have developed their own version of "huh?" because the sound is quick and simple to form, as well as being easily understood. The researchers, said that it might seem unimportant to carry out scientific research into a word like "huh?" but in fact this little word is an essential tool in human communication. They also have an answer for those who claim that "huh?" isn't a word. They say that it qualifies because of the small differences in its pronunciation in different languages. It also can be considered a word because it's something we learn to say, rather than a grunt or cry that we are born knowing how to make. The main method used in the research of "huh?" was   _  .
interviewing language experts in universities talking with people from ten different countries analyzing the recorded conversations in different languages comparing different words with the same meaning in different languages