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They face public ridicule when they make mistakes, but sport would not be the same without the commentators. And now their work is under scrutiny not just from sports fans but also from a university researcher.

Canterbury University linguistics professor Kon Kuiper has studied commentaries from the likes of cricket, ice hockey and horse racing in an effort to see how they compare.

His findings, which will come as no great surprise to sports followers, are that all commentators stick to a pretty rigid formula fitting their sports, and it is often decades before they reach their peak.

The very best commentators had to be "slightly obsessional", Professor Kuiper said.

"It is at least as difficult to become a fluent commentator as it is to learn a second language."

The voice of All Black rugby, Grant Nisbett, has done commentary for about 190 All Black tests and says he still leans a lot on the team around him.

He sees his role as describing the match play-by-play to television viewers, and leaving the more definitive comments to the former All Blacks and rugby experts around him.

"So I try to pretty much play it straight. I think some commentators in some sports ... tend to insult the viewers a bit by imposing their own ideas on them."

Professor Kuiper found gaffes common in the various sports, which he said was not surprising given the pressure commentators were under.

Nisbett said he tried not to get too hung up on his errors, or the criticism that could stem from them.

"Often you will make a mistake and you won't be aware that you have until after the game when someone points it out to you. The fact is that when you turn up to do a rugby match, it's an 80-minute ad-lib. There's nothing scripted whatsoever. People can be a little bit picky and a little bit petty at times, but it goes with the territory ... and if you can't really stomach that kind of criticism, you shouldn't be in the game."

Professor Kuiper also identified the rarity of women in sports commentary as a major issue.

"Lomu ... oh, oh"

Legendary rugby commentator Keith Quinn is lost for words as All Black wing Jonah Lomu bulldozes over English fullback Mike Catt to score one of four tries in the semi-final of the 1995 World Cup.

"The America's Cup is now New Zealand's Cup"

Yachting pundit Peter Montgomery when Team New Zealand claimed the Auld Mug in 1995.

"Germany first, Britain second and New Zealand third"

Montgomery again, this time calling it wrong after rowing twins Caroline and Georgina Evers-Swindell won Olympic gold last year.

"The bowler's Holding, the batsman's Willey"

Commentator Brian Johnston sets off fits of giggles as Michael Holding of the West Indies is bowling to Peter Willey of England in a cricket test match in 1976.

"There's nothing wrong with the car, except it's on fire"

One of many quotes from notorious Formula One racing commentator Murray Walker.