Key Points:

Watch out rest of the world - the beloved Kiwi accent is getting stronger.

From "cook me some iggs" to "my pin has run out of unk", the New Zealand accent has been the subject of much ridicule.

But detractors be warned, those beloved vowel sounds have become more distinctive over the past 30 years, and who knows where they are heading in the future.

Dr Allan Bell, Auckland University of Technology's professor of language and communication, analysed more than 300 recordings of New Zealand accents spanning a 30-year period.

He analysed the accents of ordinary New Zealanders and well-known broadcasters such as Radio New Zealand National's Nine to Noon host Kathryn Ryan.

He said the main accent change during that period had been in the vowel sounds. "There's no doubt we've moved beyond using Queen's English to adopt a broader Kiwi accent.

"If you go back to broadcasters in the 1970s, they sound like the BBC. By the time you come onto the late 1980s they are beginning to sound more Kiwi," he said.

"The Lange Labour Government of the 1980s both reflected and helped create a far more national consciousness really. So I think they had quite a lot to do with it."

He said New Zealanders had, for example, made a huge shift in the way they pronounced the vowel sound in words like "fish and chips" and "bed", which had over time become more like "fush and chups" and "bid".

But the changes were subconscious, said Dr Bell.

"It's very hard to [change], particularly vowels, consciously. You just kind of pick them up. You can use words consciously, but actually trying to do a particular pronunciation is by and large quite difficult."

And there's a bit of Cockney creeping in too. People are not fully pronouncing the "t" sound in words like "what" and "but".

Over the past 30 years, New Zealand English has become more different from other kinds of English.

"Everybody thought it would end up sounding even more Australian or more American or whatever, but in fact the things that make New Zealand English different from other dialects are increasing rather than diminishing."

Another notable change is the increased use of Maori words inserted into English.

"In the past 20 years or so words like 'iwi', 'mana' and 'whanau' have basically become part of English as well as part of Maori."

But Dr Bell said there should be more Maori and Pacific languages spoken in the mainstream media. "We have to give a place for the country's threatened languages such as te reo Maori and other languages such as Niuean and Cook Islands Maori."

Broadcasters' accents are now more in line with the general population than they were 30 years ago.

He said despite the pressure of globalisation, New Zealand English was becoming more distinctly itself.

The most distinctive differences within New Zealand English are ethnic, rather than regional.

"In countries like Britain you can tell where people come from by their accent, but that's not much the case here except for Southland.

"The differences we have are the ones that come out of, for example, Maori accents, Pacific accents or Asian accents."

He said there were some socio-economic differences relating to accent, which he suspected could be on the increase.

Dr Bell said the cultural cringe had diminished somewhat. "It used to be really strong and I'm sure that in part it still is there but I think that young Kiwis now talk the way they talk and are happy with the way they talk."