Why do some people pick up accents without even trying, while others can live in another country for decades without ever losing the sound of their mother tongue?

It’s a question that's been bothering CrowdScience listener Monica who, despite 45 years of living in the US, is still answering questions about where her accent is from. Presenter Marnie Chesterton sets off to discover why learning a new language is possible but perfecting the accent is so much harder.

Marnie speaks to a linguist about how we learn language and develop our first accent, and what we can - and can't change - about our accents. A phonetician explains to Marnie the difficulty of even hearing sounds that are not from our mother tongue, let alone replicating them. And Marnie enlists some expert help to learn some of the pitch sounds of Japanese – with mixed success.

Finally Marnie asks why people so dearly want to change their accents when doing so is such hard work. She hears from a sociolinguist about stereotypes and the impact of accent bias, and Shalu Yadav reports from the front line of Delhi call centres where workers experience prejudice about their accents regularly.

Presented by Marnie Chesterton Produced by Lorna Stewart for the BBC World Service.

Contributors: Yosiane White - Assistant Professor of Linguistics at University College Utrecht in the Netherlands Jane Setter - professor of phonetics at the University of Reading in the UK Akiko Furukawa - Reader in Japanese and Applied Linguistics at SOAS University of London in the UK Erez Levon - professor of sociolinguistics at the University of Bern in Switzerland. Shalu Yadav - BBC reporter in Delhi, India.

[Image: woman with written words coming out of mouth. Credit: Getty images]