Media playback is unsupported on your device Media caption David Sillito tests the changing sound of English pronunciation

The pronunciation of common words has changed drastically over time. So, as the British Library begins a quest to record people's articulations, what do the differences in how we pronounce words say about us?

Pedants, beware. The sound of says, ate, mischievous, harass, garage, schedule and aitch is shifting.

Once upon a time, there were gales of laughter when Frank Spencer in Some Mothers Do 'Ave 'Em pronounced harass with the emphasis on the second syllable.

Now, according to the British Library, evidence suggests that for people under the age of 35, it is becoming the favoured pronunciation.

Indeed the younger you are, the more likely you are to make says rhyme with lays rather than fez, ate rhyme with late rather than bet and to add a whole new syllable to mischievous, turning it in to miss-CHEEVY-us rather than MISS-chiv-us.

Aitch vs Haitch British English dictionaries give aytch as the standard pronunciation for the letter H. However, the pronunciation haytch is also attested as a legitimate variant. We also do not ask broadcasters who naturally say haytch to change their pronunciation but if a broadcaster contacted to ask us, we would tell them that aytch is regarded as the standard pronunciation in British English, people can feel very strongly about this and this pronunciation is less likely to attract audience complaints. Haytch is a standard pronunciation in Irish English and is increasingly being used by native English-speaking people all across the country, irrespective of geographical provenance or social standing. Polls have shown that the uptake of haytch by younger native speakers is on the rise. Schoolchildren repeatedly being told not to drop Hs may cause them to hyper-correct and insert them where they don't exist. Jo Kim BBC Pronunciation Unit Have Your Say- 'aitch' or 'haitch'- How to Say series

The British Library now wants to get a clearer idea of how spoken English is changing by recording as many people as possible reading the opening paragraph of the Mr Men book, Mr Tickle.

The library's socio-linguist Jonnie Robinson picked the passage because it's well known, easy to read and will probably be read with as "normal a voice as possible". He does not want people to put on a "posh" speaking voice.

It's part of the library's forthcoming Evolving English exhibition and aims to show how pronunciation is not a matter of right and wrong but merely fashion.

One exhibit is the BBC's guide to pronunciation from 1928. In it, it informs announcers that pristine rhymes with wine, respite is pronounced as if there were no e, combat is cumbat, finance was finn-ance. Even then some of the suggestions were becoming archaic. Not only is housewifery no longer pronounced huzzifry, it is almost entirely obsolete as a word.

Quite why some words change is unknown. Because, while many are importations from America - schedule turning into skedule is almost certainly a consequence of American films and television - the gradual shift of garage to sound like garridge is less easy to explain.

So too is there a mystery as to why certain pronunciations cause such strong feeling. Take the eighth letter of the alphabet, pronounce it haitch and then look for the slightly agonised look in some people's eyes.

One suggestion is that it touches on a long anxiety in English over the letter aitch. In the 19th Century, it was normal to pronounce hospital, hotel and herb without the h. Nowadays "aitch anxiety" has led to all of them acquiring a new sound, a beautifully articulated aitch at the beginning. America has perhaps hung on to its aitchless herb because it has less class anxiety attached to pronunciations.

Generational divide Language change happens through innovation - each generation talks slightly differently from the one before. So we hear a "pronunciation divide" between the young and the old with forms like aitch and haitch. Children's first exposure to English is usually through their parents, but once at school, the words and pronunciations they adopt are more influenced by other children they spend all day with. It's a human thing to adapt to the group in this way. We also gradually change borrowed words, like village and garage from French, to fit a more English pronunciation - with an -idge sound in the last syllable. Village is much further along in this ongoing process and therefore less controversial. Languages have always been alive and evolving to suit the users' communication needs, and it's not a bad thing to have change like this. Jon Herring, British Library

However, the link between class, voice and status is not what it once was. Many of us are barely aware of how we say says or ate or what was once considered the right and proper way.

It marks a decline in class anxiety in speech; attitudes to accents and pronunciations have become much more relaxed.

However, there are some pronunciations that do inspire ridicule and prejudice. If you rhyme cloth, wrath and off with north and wharf then you are in a small and declining tribe.

The shift from the "received pronunciation" of the 1930s and 40s is well documented but one example of how far it has fallen out of favour is that in the forthcoming BBC costume drama, South Riding, the Yorkshire accents of the 1930s pass without comment but the voices that would have been classic "RP" in the book have been updated.

Audiences, it is argued, simply could not sit through a drama and care about a character if they sounded that "posh". They would be too busy laughing.