Northern accents could start dying out within the next 45 years as a result of the rising dominance of southern ones, according to a Cambridge University study.
Children living in towns and cities across the North of England are increasingly using pronunciations more usually spoken in the South because they are easier to pick up, researchers say.
It means some northern speech patterns for words such as "strut" (which rhymes with "foot") and "singer" (rhymes with "finger") could soon be lost.
But some words like "bath", often said with a short "a" by people from the north compared to a longer "a" by those in the south, remain so strongly entrenched that they are likely to survive.
Accents most commonly heard in the South West are also at risk as West Country dialects which produce pirate-like "arrr" sounds in words like farm are replaced with a softer "aah".
The findings came after researchers from the universities of Cambridge and Portsmouth built a physics-based model to determine the future of the English language.
Words that will only be pronounced like a southerner in 45 years
They examined data from a 1950s study by the Survey of English Dialects and compared it with a 2016 study of 50,000 English speakers carried out by the English Dialect App.
Analysis shows the pronunciation of words in South East England has already replaced northern versions over previous decades and will eventually become standard across the country.
As an example, the word "thawing" was commonly pronounced "thaw-wing" at the start of the 20th century but now the majority of people say it with an intrusive "r", which means it sounds like "thaw-ring".
"We found that the word has changed because it was tricky to pronounce and children are more likely to pick up the easier pronunciation. This then becomes the norm," said Dr James Burridge, from the University of Portsmouth.
Modelling accounted for people who move around their home area and travel further afield, perhaps for work or to move in with a spouse, and was run using updated information on population distributions and migration patterns.
Experts say the results can help predict how the English language will evolve over the next 40 years.
Dr Tamsin Blaxter, from the University of Cambridge, said: "It’s exciting that models from physics can be used to explain what we have observed about changing dialects, and even make predictions about the future."
According to the researchers, while pronunciations across England are becoming increasingly southernised, dialectal variations between the regions are also fading.
For example, some words like "backend" – spoken in areas of Yorkshire to describe autumn – will completely disappear within 20 years, it was predicted.
Another word for autumn, "fall", has already largely disappeared from its traditional region in the South West, although it is used widely in North America.
However, Dr Blaxter insisted the linguistic changes would not result in northerners completely losing their accents.
"An ‘accent’ would refer to the pronunciation of all words of the language, and what we see are changes happening in big classes of words – but not all of them," she said.
"So, northerners have not and are not going to totally alter their accents – but some groups of words are shifting to sound more like southerners, and we project that those changes will continue, to the point that some northern pronunciations are likely to disappear."
The research was published in Journal of Physics: Complexity.