"How do accents start and where did they come from?” asks Sachin Bahal from Toronto in Canada.
Hannah is schooled in speaking Geordie by top accent coach Marina Tyndall. And Adam talks to author and acoustics expert Trevor Cox about how accents evolved and why they persist.
We meet Debie who has Foreign Accent Syndrome - an extremely rare condition in which your accent can change overnight. After a severe bout of flu, which got progressively worse, Debie's Brummie accent suddenly transformed into something distinctively more European.
If you have any more Curious Cases for the team to solve, please send them in for consideration: curiouscases@bbc.co.uk
Presenters: Adam Rutherford, Hannah Fry
Producer: Michelle Martin
First broadcast on BBC Radio 4 in November 2018.