Siren noise Citroen Berlingo 2010

[critterchum]

Hello,

I have a 2010 Citroen Berlingo Multispace and am getting a siren noise when accelerating! When I first got the car (few weeks ago) I thought I could here the police behind me! The noise is subtle and not very loud. I get first part of the siren noise when I accelerate and when I take my foot off to change gear I get the other part of the siren noise! Does this make sense? Possibly more noticible from cold.
Is it an air intake thing? and is this normal. I have two months warranty left, do I need to get it checked out?
Thanks

[ecohouse1]

Probably the Turbo (Assuming a diesel) - its most noticable when accelerating with the window open while driving alongside a wall/fence. I wouldn't worry about it.