Why do people shout on their cellphones?

How does traffic jam? And, why do some people shout into their cellphones in public places? Two subjects guaranteed to annoy even the most patient listeners.

The Phantom Jam Listener Matthew Chandler wrote to us: "I travel on the motorway for work and often I find myself sitting in a traffic jam for ages, thinking there must be roadworks or an accident ahead, then suddenly the jam mysteriously disappears to reveal… nothing! There's no apparent reason whatsoever."

Doctors Rutherford and Fry discover the cause of these phantom jams. Adam ventures on to the M25 in search of a tailback, and Hannah looks at projects around the world designed to thwart traffic tailbacks.

This case features Neal Harwood from the Transport Research Laboratory and BBC technology reporter, Jane Wakefield. Plus a special guest appearance from Greg Marston, aka 'Masdar City Man'.

The Aural Voyeur Listener Daniel Sarano, from New Jersey, asks why people shout on their mobile phones in public: "I have no interest in hearing about people’s private lives. I don’t enjoy the aural voyeurism. If people want to say 'honey I’m running late, be home in 5'. That’s OK, but discussing business or, worse, personal details…. I hate it. The whole idea would have seemed an anathema to older generations. I think they would have considered it rude to talk loudly in public. No sense of that in the 21st Century.”

We discover the answer to this annoying modern habit by delving into the inner workings of telephony. What follows is a tale of engineering rivalry, Victorian etiquette and early otolaryngology. Providing the answers are acoustic technologist Nick Zakarov and historian Greg Jenner, author of 'A Million Years in a Day: A Curious History of Daily Life'.

If you have any everyday mysteries for the team to investigate using the power of science, please email [email protected]

Producer: Michelle Martin

Image: A man on a phone, Credit: Thinkstock